Method for controlling connected mode DRX operations

ABSTRACT

A method in a UE comprises monitoring a downlink control channel during a duration of at least a first timer, and receiving an indication of a downlink or uplink transmission for the UE. The method comprises after receiving the indication of the downlink or uplink transmission for the UE, stopping monitoring the first timer, wherein after the first timer is stopped the UE does not need to monitor the downlink control channel. The method comprises performing an uplink transmission associated with the indicated downlink or uplink transmission for the UE. The method comprises starting a second timer after receiving the indication for the downlink or uplink transmission for the UE, the duration of the second timer comprising an offset period, and, when the second timer expires, starting a third timer. The UE monitors the downlink control channel for the duration of the third timer.

PRIORITY

This application claims priority to U.S. Patent Provisional ApplicationNo. 62/277,202 filed on Jan. 11, 2016, entitled “Method for ControllingConnected Mode DRX Operations,” the disclosure of which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates, in general, to wireless communicationsand, more particularly, to methods for controlling connected modediscontinuous reception operations.

BACKGROUND

Narrow Band Internet-of-Things (NB-IoT) is a narrowband (180 KHzbandwidth) system being developed for cellular Internet-of-Things (IoT)by the Third Generation Partnership Project (3GPP). The system is basedon Long Term Evolution (LTE) systems, and addresses optimized networkarchitecture and improved indoor coverage for a massive number ofdevices with any of the following characteristics: low throughput (e.g.,2 Kbps); low delay sensitivity (e.g., ˜10 seconds); ultra-low devicecost (e.g., below 5 dollars); and low device power consumption (e.g.,battery life of 10 years).

It is envisioned that each cell (e.g., ˜1 Km²) in this system will servethousands (e.g., ˜50,000) devices such as sensors, meters, actuators,and other devices. It is imperative that this system be able to providegood coverage for its devices, which are often located deep indoors(e.g., underground in basements, or even built into walls of a building)and have limited or no possibility for battery charging. Although manydifferent types of devices are envisioned, for the sake of simplicitythey will be interchangeably referred to herein as user equipment (UEs)or wireless devices.

In order to make it possible to deploy NB-IoT using only one re-farmedGSM carrier and support lower manufacturing costs for NB-IoT UEs, thebandwidth has been reduced to one physical resource block (PRB) of size180 KHz divided into several subcarriers.

For frequency division duplex (FDD) (i.e., the transmitter and thereceiver operate at different carrier frequencies), only half-duplexmode needs to be supported in the UE. The lower complexity of thedevices (e.g., only one transmission/receiver chain) means that somerepetition might also be needed in normal coverage. Further, toalleviate UE complexity, the working assumption is to havecross-subframe scheduling. That is, a transmission is first scheduled onan Enhanced Physical Downlink Control Channel (E-PDCCH, also known asnarrowband Physical Downlink Control Channel (NB-PDCCH or NPDCCH). Then,the first transmission of the actual data on the narrowband PhysicalDownlink Shared Channel (NB-PDSCH or NPDSCH) is carried out after thefinal transmission of the NB-PDCCH. Similarly, for uplink (UL) datatransmission, information about resources scheduled by the network andneeded by the UE for UL transmission is first conveyed on the NB-PDCCHand then the first transmission of the actual data by the UE on thenarrowband Physical Uplink Shared Channel (NB-PUSCH or NPUSCH) iscarried out after the final transmission of the NB-PDCCH. In otherwords, for both cases above, there is no simultaneous reception ofcontrol channel and reception/transmission of data channel from the UE'sperspective.

In legacy cellular communication systems like High Speed Packet Access(HSPA) and LTE, a re-transmission procedure called Hybrid AutomaticRepeat reQuest (HARQ) with soft combining is supported. After a datablock is transmitted in one direction (e.g., between a UE and a radiobase station) feedback on the decoding result is usually transmitted inthe reverse direction, denoted as a HARQ feedback message. This feedbackmessage is typically either a “binary” decoding result or a schedulinggrant/assignment message. In cases where the feedback is a “binary”decoding result, the feedback may be in the form of an acknowledgement(ACK) indicating that data block decoding was successful, or a negativeacknowledgement (NACK) indicating that data block decoding wasunsuccessful. In cases where the feedback is in the form of a schedulinggrant/assignment message, the scheduling grant/assignment message mayrequest either a re-transmission (in the event that data block decodingis unsuccessful, similar to the NACK described above) or a transmissionof a new data block that implicitly acknowledges that the previous datablock was successfully decoded (similar to the ACK described above).

In some cases, HARQ feedback information could also be indicated by notransmission (DTX). In such a scenario, no transmission means either ACKor NACK (typically the latter) and transmitting something (e.g., apreamble or some other signal/code) could indicate an ACK. Lack oftransmitting a HARQ feedback message could also be possible to indicateeither a successful or unsuccessful decoded data block (i.e., ACK orNACK). The HARQ feedback (or lack of it) then triggers there-transmission, or, if the data was received successfully and more datais available, a new data transmission could be started.

Typically, multiple so-called HARQ processes are used in parallel (e.g.,in HSPA and LTE). A HARQ process is a stop-and-wait (SAW) HARQ entitythat independently transfers data packets and waits for HARQ feedbackbefore either a re-transmission or a new transmission is transmitted. Inlegacy LTE FDD, typically eight HARQ processes are supported perdirection. The same applies to HSPA with 2 ms UL transmission timeinterval (TTI).

Synchronous HARQ operation means the retransmissions occur at a fixedtime after the previous transmission. In asynchronous HARQ operation, onthe other hand, the retransmissions can occur at any time after aprevious transmission. In both legacy LTE and in HSPA, the UL usessynchronous HARQ and the downlink (DL) uses asynchronous HARQ.

To reduce UE battery consumption, a concept called connected modediscontinuous reception (DRX) is used, which allows the UE to go intosleep mode (i.e., no reception and/or transmission is required) duringconnected mode in LTE. The main idea is that when there has not been anytransmission and/or reception activity (e.g., notransmissions/re-transmissions and no pending re-transmissions) for aperiod of time, the UE can go into sleep mode and only needs to be awakeperiodically for a short amount of time every DRX cycle to monitor theDL control channel. If new UL data becomes available, the UE can wake upat any time but needs to inform the network through configured ULresources (for example, a scheduling request could be triggered to besent on Physical Uplink Control Channel (PUCCH)).

The DRX operation is defined in 3GPP TS 36.321, v. 13.0.0 for legacy LTEand controlled by a set of timers/parameters that are either pre-definedor sent to the UE. Specifically: onDurationTimer; drxStartOffset (fromlongDRX-CycleStartOffset in 3GPP TS 36.331, v. 13.0.0); longDRX-Cycle(from longDRX-CycleStartOffset in 3GPP TS 36.331, v. 13.3.0);shortDRX-Cycle; drxShortCycleTimer; drx-InactivityTimer; HARQ-RTT-Timer;and drx-RetransmissionTimer. Herein, citations to a particular versionof the standard (e.g., TS 36.331, v. 13.0.0) are intended asrepresentative versions available when the application was originallyfiled. However, other versions may also apply, as appropriate.

FIG. 1 illustrates an example of UE operation during connected mode DRX.More particularly, FIG. 1 (which is reproduced from 3GPP TS 36.321, v.13.0.0) illustrates when the UE needs to be awake and monitor the DLcontrol channel (denoted as PDCCH in the example of FIG. 1, but could bePDCCH and/or ePDCCH) during connected mode DRX cycle 105. In general,during DRX cycle 105 the UE monitors the DL control channel duringOnDuration period 110 and sleeps during Opportunity for DRX 115. If newdata is scheduled (in either UL or DL) during the OnDuration time 105,the UE goes out of DRX and starts a timer called drx-InactivityTimer.

FIG. 2 illustrates an example of legacy DRX operation. If new data 205is scheduled (by DL control channel 210), drx-InactivityTimer 215 willbe re-started, otherwise it will eventually expire and the UE entersDRX. In the example of FIG. 2, the UE enters DRX upon expiry ofdrx-InactivityTimer 215 if it has not detected PDCCH during the durationof drx-InactivityTimer 215. In addition, FIG. 2 illustrates the offset220 between the HARQ data 205 (shown in the example of FIG. 2 as “NewData” 205) and the HARQ feedback 225 (shown in FIG. 2 as ACKtransmission 225 in the UL 230). In LTE, offset between the HARQ data205 and the HARQ feedback 225 is always N+4, i.e., always 4 ms (orequivalently sub-frames) after the data transmission at time occasion N.

FIG. 3 illustrates an example of legacy DRX operation if there are DLre-transmissions. In such a scenario, the UE uses two other timers:HARQ-RTT-Timer 305 and drx-RetransmissionTimer 310 to supervise there-transmission(s). Note that these timers are independent ofdrx-InactivityTimer 215. When the re-transmission (shown in FIG. 3 asReTx 315) is successfully decoded, drx-Retransmission Timer 310 isstopped/cancelled, as shown in the example of FIG. 3. Note that in theexample of FIG. 3, after “New Data” 205 there could be activity forother UL/DL HARQ processes signaled on the PDCCH. If new data isscheduled on any of those, drx-InactivityTimer 215 is re-started.

FIG. 4 illustrates an example of legacy DRX operation when there is anUL re-transmission. In the example of FIG. 4, the UE receives UL grant405 on DL control channel 410 while OnDuration Timer 410 is running.Upon receiving UL grant 405, the UE stops OnDuration Timer 410 andstarts drx-InactivityTimer 215. In the example of FIG. 4, the UEperforms UL transmission 420 (shown as “New Data” in the example of FIG.4) associated with UL grant 405. After performing the UL transmission420, the UE will enter DRX upon expiry of drx-InactivityTimer 215 if itdoes not detected PDCCH during the duration of drx-InactivityTimer 215.

In legacy LTE, no retransmission timers are needed if there is an ULre-transmission 425, as synchronous HARQ is used. Synchronous HARQprovides the exact timing on when the HARQ feedback (e.g., ACK 435and/or NACK 430) and the re-transmission is scheduled. A new grant on DLcontrol channel 410 (e.g., PDCCH) could also be given at the samesub-frame as NACK 430 is sent on the Physical Hybrid Indicator Channel(PHICH) and then the re-transmission is called “adaptive.” The N+4offsets between UL grant 405 and UL transmission 420, between uplinktransmission 420 and NACK 430, between NACK 430 and UL retransmission425, and between UL retransmission 425 and ACK 435 are shown as elements220 a, 220 b, 220 c, and 220 d, respectively.

Note that in the example of FIG. 4, after UL grant 405 there could beactivity for other UL/DL HARQ processes signaled on downlink controlchannel 410 (e.g., PDCCH). If new data is scheduled on any of those, thedrx-InactivityTimer is re-started (if used/running). Note, also that insome cases ACK 435 could also be an implicit acknowledgement, forexample if a grant for new data is given for the HARQ process.

In 3GPP Release 13, a work item for enhanced Machine-Type Communication(eMTC) has been ongoing, in which changes have been made to HARQoperations as compared to legacy LTE. It has been decided that threeparallel HARQ processes are supported. In addition, the UL HARQ has beenchanged from synchronous to asynchronous, and HARQ feedback is onlyimplicit and received on M-PDCCH (i.e., no PHICH channel exists)earliest N+4 after the PUSCH transmission. As a result, changes areneeded to how the UE should enter DRX when there is a re-transmission,as the timing of the HARQ feedback is no longer fixed.

In another work item in 3GPP Release 13 related to licensed-assistedaccess (LAA), it has also been identified that the UL HARQ needs to bechanged from synchronous to asynchronous compared to legacy LTE. Theimpact of this is described in detail in 3GPP TR 36.889, v. 13.0.0 (andin particular section 7.2.2.2), which is hereby incorporated byreference in its entirety.

In LTE/eMTC all DRX parameters are semi-statically configured in the UEbased on Radio Resource Control (RRC) signaling. Some dynamic change issupported through Medium Access Control (MAC) signaling to control theUE entering short/long DRX during the “Active time.”

A problem with existing approaches is that the HARQ/DRX design has beenoptimized for multiple HARQ processes and use cases where low latency isimportant and minimizing UE battery consumption has not been the maingoal. If the same design is applied to a UE that only supportshalf-duplex operations, cross subframe scheduling and only one HARQprocess, it would result in the UE being awake for a longer time thannecessary for many traffic use cases that are typically used in MTC/IoTapplications. For example, in many of the traffic use cases there are nosimultaneous UL and DL data transfers. Instead, most use cases rely on arequest-response type of traffic pattern where an IP packet is sent inone direction followed by a response in the other.

Further, according to existing approaches (both LTE and HSPA) the HARQoperation in the UL is synchronous. If the HARQ operation is changed toasynchronous, it is not known how long the UE shall wait for HARQfeedback after a transmission/re-transmission has been done. Oneapproach would be to copy the DL design also for the UL (i.e., introducesimilar timers (e.g., HARQ-RTT-Timer/drx-RetransmissionTimer) also forthe UL). Although such an approach might be acceptable for legacy LTEuse cases, it is not well suited for use cases in the area of MTC/IoT.These applications involve the use of new, simplified UEs with supportfor only half-duplex, one HARQ process and cross-subframe scheduling.Thus, a more optimized solution is desirable. The reason for this isthat other solutions could reduce the UE battery/power consumption andtherefore perform better if the properties of half-duplex, one HARQprocess, only cross sub-frame scheduling and typical traffic patternsare utilized in the design.

One goal of NB-IoT is to re-use the legacy LTE (including eMTC changes)as much as possible. An important consideration is how the HARQ andconnected mode DRX operations should work. If the legacy design isapplied on NB-IoT this would lead to larger battery/power consumptionfor the UE. Further, since all the DRX-related timers are semi-static,there is very limited flexibility for the eNB to schedule HARQtransmissions/re-transmissions and HARQ feedbacks. If many UEs and/orUEs with different coverage levels (and thus different transmissionduration times) need to be served, the previous approaches of havingsemi-static parameters are not flexible enough to enable short “activetime” for UEs. Applying the same design as in legacy LTE would requirethe use of larger timer values, and thus the UE awake time would belonger resulting in larger battery/power consumption.

SUMMARY

To address the foregoing problems with existing solutions, disclosed isa method in a user equipment (UE). The method comprises monitoring adownlink control channel during a duration of at least a first timer.The method comprises receiving, on the monitored downlink controlchannel, an indication of a downlink or uplink transmission for the UE.The method comprises after receiving the indication of the downlink oruplink transmission for the UE, stopping monitoring the first timer,wherein after the first timer is stopped the UE does not need to monitorthe downlink control channel. The method comprises performing an uplinktransmission associated with the indicated downlink or uplinktransmission for the UE. The method comprises starting a second timer,after receiving the indication of the downlink or uplink transmissionfor the UE, the duration of the second timer comprising an offsetperiod. The method comprises when the second timer expires, starting athird timer, wherein the UE monitors the downlink control channel forthe duration of the third timer.

In certain embodiments, the second timer may be started either: afterperforming the associated uplink transmission; or at the end of thereceived indication of the downlink or uplink transmission for the UE.

In certain embodiments, the method may comprise entering a discontinuousreception mode when the third timer expires. The method may comprisereceiving a message including information about a duration of at leastone of the second and third timers. In certain embodiments, the firsttimer may be an onDurationTimer of a discontinuous reception cycle. Incertain embodiments, at least one of the first timer and the third timermay be a drx-InactivityTimer. In certain embodiments, at least one ofthe first timer and the third timer may comprise a discontinuousreception retransmission timer. In certain embodiments, the second timermay be a Hybrid Automatic Repeat reQuest (HARQ)-Round Trip Time (RTT)timer that comprises the offset period.

In certain embodiments, the indication of the downlink or uplinktransmission for the UE may comprise a downlink scheduling assignment,and the uplink transmission associated with the indicated downlinktransmission may comprise an acknowledgement message. In certainembodiments, the indication of the downlink or uplink transmission forthe UE may comprise an uplink grant, and the uplink transmissionassociated with the indicated uplink transmission may comprise a datatransmission in the uplink. In certain embodiments, the indication ofthe downlink or uplink transmission for the UE may comprise informationabout a duration of at least one of the second and third timers.

Also disclosed is a user equipment (UE). The UE comprises processingcircuitry. The processing circuitry is configured to monitor a downlinkcontrol channel during a duration of at least a first timer. Theprocessing circuitry is configured to receive, on the monitored downlinkcontrol channel, an indication of a downlink or uplink transmission forthe UE. The processing circuitry is configured to, after receiving theindication of the downlink or uplink transmission for the UE, stopmonitoring the first timer, wherein after the first timer is stopped,the UE does not need to monitor the downlink control channel. Theprocessing circuitry is configured to perform an uplink transmissionassociated with the indicated downlink or uplink transmission for theUE. The processing circuitry is configured to start a second timer afterreceiving the indication of the downlink or uplink transmission for theUE, the duration of the second timer comprising an offset period. Theprocessing circuitry is configured to, when the second timer expires,start a third timer, wherein the UE monitors the downlink controlchannel for the duration of the third timer.

Also disclosed is a method in a network node. The method comprisesdetermining a duration of a first timer and a duration of a secondtimer, the first and second timers for use by a user equipment (UE) tocontrol discontinuous reception operation, wherein the duration of thefirst timer comprises an offset period. The method comprises sending, tothe UE, information about the duration of the first timer and theduration of the second timer.

In certain embodiments, sending, to the UE, information about theduration of the first timer and the duration of the second timer maycomprise sending a message to the UE including the information about theduration of the first timer and the duration of the second timer.

In certain embodiments, the information about the duration of the firsttimer and the duration of the second timer may be included in anindication of a downlink or uplink transmission for the UE. The methodmay comprise sending, to the UE, an indication of a downlink or uplinktransmission for the UE, and receiving, from the UE, an uplinktransmission associated with the indicated downlink or uplinktransmission for the UE. In certain embodiments, the indication of thedownlink or uplink transmission for the UE may comprise a downlinkscheduling assignment, and the uplink transmission associated with theindicated downlink transmission may comprise an acknowledgement message.In certain embodiments, the indication of the downlink or uplinktransmission for the UE may comprise an uplink grant, and the uplinktransmission associated with the indicated uplink transmission maycomprise a data transmission in the uplink.

In certain embodiments, the duration of the first timer comprises oneof: an amount of time that the UE waits after sending the uplinktransmission associated with the indicated downlink or uplinktransmission for the UE before the UE starts the second timer; and anamount of time that the UE waits after the end of the indication of thedownlink or uplink transmission for the UE before the UE starts thesecond timer. In certain embodiments, the first timer may be a HybridAutomatic Repeat reQuest (HARQ)-Round Trip Time (RTT) timer. In certainembodiments, the duration of the second timer may comprise an amount oftime that the UE monitors a downlink control channel before entering adiscontinuous reception mode. In certain embodiments, the second timermay be a drx-InactivityTimer.

Also disclosed is a network node. The network node comprises processingcircuitry. The processing circuitry is configured to determine aduration of a first timer and a duration of a second timer, the firstand second timers for use by a user equipment (UE) to controldiscontinuous reception operation, wherein the duration of the firsttimer comprises an offset period. The processing circuitry is configuredto send, to the UE, information about the duration of the first timerand the duration of the second timer.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, certain embodiments mayadvantageously reduce UE battery and/or power consumption compared toexisting approaches. As another example, certain embodiments mayadvantageously reduce the time the UE needs to be awake to monitor thedownlink control channel. As still another example, the amount of timethe UE needs to be awake to monitor the downlink control channel can beadapted to the present scheduling situation in the network node (forexample, an eNB). As yet another example, because the downlink controlchannel in NB-IoT needs to be time multiplexed both between UEs and withtransmissions on the downlink shared channel, certain embodiments mayadvantageously enable time multiplexing of the “active time” for UEs,which may increase scheduling flexibility in the network node and allowthe UEs to be awake during smaller (i.e., shorter time durations). Otheradvantages may be readily apparent to one having skill in the art.Certain embodiments may have none, some, or all of the recitedadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed embodiments and theirfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates an example of UE operation during connected mode DRX;

FIG. 2 illustrates an example of legacy DRX operation;

FIG. 3 illustrates an example of legacy DRX operation if there are DLre-transmissions;

FIG. 4 illustrates an example of legacy DRX operation when there is anUL re-transmission;

FIG. 5 is a block diagram illustrating an embodiment of a network 500,in accordance with certain embodiments;

FIG. 6A illustrates a first example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments;

FIG. 6B illustrates a variation of the first example of timing andtransmission for controlling DRX operations in FIG. 6A, in accordancewith certain embodiments;

FIG. 7A illustrates a second example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments;

FIG. 7B illustrates a variation of the second example of timing andtransmission for controlling DRX operations in FIG. 7A, in accordancewith certain embodiments;

FIG. 8A illustrates a third example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments;

FIG. 8B illustrates a variation of the third example of timing andtransmission for controlling DRX operations in FIG. 8A, in accordancewith certain embodiments;

FIG. 9A illustrates a fourth example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments;

FIG. 9B illustrates a variation of the fourth example of timing andtransmission for controlling DRX operations in FIG. 9A, in accordancewith certain embodiments;

FIG. 10 is a flow chart of an example of DRX operations, in accordancewith certain embodiments;

FIG. 11 is a flow diagram of a method in a UE, in accordance withcertain embodiments;

FIG. 12 is a flow diagram of a method in a network node, in accordancewith certain embodiments;

FIG. 13 is a block schematic of an exemplary UE, in accordance withcertain embodiments;

FIG. 14 is a block schematic of an exemplary network node, in accordancewith certain embodiments;

FIG. 15 is a block schematic of an exemplary radio network controller orcore network node, in accordance with certain embodiments;

FIG. 16 is a block schematic of an exemplary UE, in accordance withcertain embodiments; and

FIG. 17 is a block schematic of an exemplary network node, in accordancewith certain embodiments.

DETAILED DESCRIPTION

As described above, one important consideration is how the HARQ andconnected mode DRX operations should work in NB-IoT. Existingapproaches, such as those used in legacy LTE, are not acceptable for theuse cases associated with NB-IoT operations. For example, if the legacydesign is applied on NB-IoT, this would lead to larger battery and/orpower consumption for the UE. Furthermore, since all the DRX-relatedtimers are semi-static, there is very limited flexibility for the eNB toschedule HARQ transmissions/re-transmissions and HARQ feedbacks. If manyUEs and/or UEs with different coverage levels (and thus differenttransmission duration times) need to be served, the existing approacheshaving semi-static parameters are not flexible enough to enable short“Active time” for UEs. Applying the existing approaches used in legacyLTE to NB-IoT use cases would therefore necessitate the use of largertimer values, which would have the undesirable consequence of increasingthe amount of time the UE is required to be awake and, in turn, resultin larger battery and/or power consumption by the UE.

The present disclosure contemplates various embodiments that may addressthese and other deficiencies associated with existing approaches. Incertain embodiments, the deficiencies associated with existingapproaches may be overcome using a new, flexible way ofhandling/controlling the “active time” (i.e., the time a UE needs to beawake to monitor a DL control channel) in connected mode for NB-IoT.Generally, two parameters may be used for this: an “active time” thatdetermines how long the UE should be awake to monitor the DL controlchannel before going into DRX; and an “offset time” that determines whento start the “active time.” In some cases, the “offset time” is setrelative to an UL transmission that was triggered by receiving a controlmessage on the DL control channel (e.g., NB-PDCCH). In one non-limitingexample, the UL transmission may be either a HARQ feedback messageassociated with a DL assignment for receiving DL data or an UL grantresulting in an UL transmission of UL data. If a new control message isreceived on the DL control channel during the “active time,” the “activetime” is stopped (i.e., the UE does not need to be awake to monitor theDL control channel). Then, the activity indicated by the control message(DL-assignment or UL-grant) is performed, and new “active time” and“offset time” parameters are used. Information about the values of thetwo parameters (“active time” and “offset time”) may be provided in anysuitable manner. In certain embodiments, the information about thevalues of the two parameters may be provided per transmission as part ofthe DL-assignment/UL-grant message sent on the DL control channel, andmay vary in-between different DL-assignments/UL-grants.

Aspects of the embodiments described herein are directed to methodsperformed by a UE in a communication system (e.g., NB-IoT) that controlsthe connected mode DRX operation and behavior for the UE and a networknode (e.g., a radio base station/eNB). In certain embodiments, themethod utilizes the properties of the communication capabilities of theNB-IoT devices described above (e.g., half-duplex, one HARQ process,cross-sub-frame scheduling) and typical traffic patterns used tooptimize the “active time” for the device (UE) in order to minimize thebattery and/or power consumption. Certain embodiments may alsoadvantageously introduce a flexible way of controlling the connectedmode DRX operations by dynamically signaling the involved parameters.

According to one example embodiment, a method in a UE is disclosed. TheUE monitors a DL control channel during a duration of at least a firsttimer. The UE receives, on the monitored DL control channel, anindication of a DL or UL transmission for the UE. After receiving theindication of the DL or UL transmission for the UE, the UE stopsmonitoring the first timer, wherein after the first timer is stopped,the UE does not need to monitor the downlink control channel. The UEperforms an UL transmission associated with the indicated DL or ULtransmission for the UE. The UE starts a second timer after receivingthe indication for the downlink or uplink transmission for the UE, theduration of the second timer comprising an offset period. In certainembodiments, the second timer may be started either: after performingthe associated UL transmission; or at the end of the received indicationof the DL or UL transmission for the UE. When the second timer expires,the UE starts a third timer, wherein the UE monitors the downlinkcontrol channel for the duration of the third channel. In certainembodiments, the UE may enter a discontinuous reception mode when thethird timer expires. In certain embodiments, the UE may receive amessage including information about a duration of at least one of thesecond and third timers.

According to another example embodiment, a method in a network node isdisclosed. The network node determines a duration of a first timer and aduration of a second timer, the first and second timers for use by a UEto control discontinuous reception operation, wherein the duration ofthe first timer comprises an offset period. In certain embodiments, theduration of the first timer may comprise one of: an amount of time thatthe UE waits after sending the uplink transmission associated with theindicated downlink or uplink transmission for the UE before the UEstarts the second timer; and an amount of time that the UE waits afterthe end of the indication of the downlink or uplink transmission for theUE before the UE starts the second timer. In certain embodiments, theduration of the second timer may comprise an amount of time that the UEmonitors a DL control channel before entering a discontinuous receptionmode. The network node sends, to the UE, information about the durationof the first timer and the duration of the second timer. As onenon-limiting example, the network node may send a message to the UEincluding the information about the duration of the first timer and theduration of the second timer. In some cases, the information about theduration of the first timer and the duration of the second timer may beincluded in an indication of a DL or UL transmission for the UE.

FIG. 5 is a block diagram illustrating an embodiment of a network 500,in accordance with certain embodiments. Network 500 includes one or moreUE(s) 510 (which may be interchangeably referred to as wireless devices510) and one or more network node(s) 515 (which may be interchangeablyreferred to as eNBs 515). UEs 510 may communicate with network nodes 515over a wireless interface. For example, a UE 510 may transmit wirelesssignals to one or more of network nodes 515, and/or receive wirelesssignals from one or more of network nodes 515. The wireless signals maycontain voice traffic, data traffic, control signals, and/or any othersuitable information. In some embodiments, an area of wireless signalcoverage associated with a network node 515 may be referred to as a cell525. In some embodiments, UEs 510 may have device-to-device (D2D)capability. Thus, UEs 510 may be able to receive signals from and/ortransmit signals directly to another UE.

In certain embodiments, network nodes 515 may interface with a radionetwork controller. The radio network controller may control networknodes 515 and may provide certain radio resource management functions,mobility management functions, and/or other suitable functions. Incertain embodiments, the functions of the radio network controller maybe included in network node 515. The radio network controller mayinterface with a core network node. In certain embodiments, the radionetwork controller may interface with the core network node via aninterconnecting network 520. Interconnecting network 520 may refer toany interconnecting system capable of transmitting audio, video,signals, data, messages, or any combination of the preceding.Interconnecting network 520 may include all or a portion of a publicswitched telephone network (PSTN), a public or private data network, alocal area network (LAN), a metropolitan area network (MAN), a wide areanetwork (WAN), a local, regional, or global communication or computernetwork such as the Internet, a wireline or wireless network, anenterprise intranet, or any other suitable communication link, includingcombinations thereof.

In some embodiments, the core network node may manage the establishmentof communication sessions and various other functionalities for UEs 510.UEs 510 may exchange certain signals with the core network node usingthe non-access stratum layer. In non-access stratum signaling, signalsbetween UEs 510 and the core network node may be transparently passedthrough the radio access network. In certain embodiments, network nodes515 may interface with one or more network nodes over an internodeinterface, such as, for example, an X2 interface.

As described above, example embodiments of network 500 may include oneor more UEs 510, and one or more different types of network nodescapable of communicating (directly or indirectly) with UEs 510.

In some embodiments, the non-limiting term UE is used. UEs 510 describedherein can be any type of wireless device capable of communicating withnetwork nodes 515 or another UE over radio signals. UE 510 may also be aradio communication device, target device, D2D UE,machine-type-communication UE or UE capable of machine to machinecommunication (M2M), low-cost and/or low-complexity UE, a sensorequipped with UE, Tablet, mobile terminals, smart phone, laptop embeddedequipped (LEE), laptop mounted equipment (LME), USB dongles, CustomerPremises Equipment (CPE), etc. UE 510 may operate under either normalcoverage or enhanced coverage with respect to its serving cell. Theenhanced coverage may be interchangeably referred to as extendedcoverage. UE 510 may also operate in a plurality of coverage levels(e.g., normal coverage, enhanced coverage level 1, enhanced coveragelevel 2, enhanced coverage level 3 and so on). In some cases, UE 510 mayalso operate in out-of-coverage scenarios.

Also, in some embodiments generic terminology, “radio network node” (orsimply “network node”) is used. It can be any kind of network node,which may comprise a base station (BS), radio base station, Node B,multi-standard radio (MSR) radio node such as MSR BS, evolved Node B(eNB), network controller, radio network controller (RNC), base stationcontroller (BSC), relay node, relay donor node controlling relay, basetransceiver station (BTS), access point (AP), radio access point,transmission points, transmission nodes, Remote Radio Unit (RRU), RemoteRadio Head (RRH), nodes in distributed antenna system (DAS),Multi-cell/multicast Coordination Entity (MCE), core network node (e.g.,MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g., E-SMLC), MDT, orany other suitable network node.

The terminology such as network node and UE should be considerednon-limiting and does in particular not imply a certain hierarchicalrelation between the two; in general “eNodeB” could be considered asdevice 1 and “UE” device 2, and these two devices communicate with eachother over some radio channel.

Example embodiments of UE 510, network nodes 515, and other networknodes (such as radio network controller or core network node) aredescribed in more detail below with respect to FIGS. 13-17.

Although FIG. 5 illustrates a particular arrangement of network 500, thepresent disclosure contemplates that the various embodiments describedherein may be applied to a variety of networks having any suitableconfiguration. For example, network 500 may include any suitable numberof UEs 510 and network nodes 515, as well as any additional elementssuitable to support communication between UEs or between a UE andanother communication device (such as a landline telephone).Furthermore, although certain embodiments may be described asimplemented in a Long Term Evolution (LTE) network, the embodiments maybe implemented in any appropriate type of telecommunication systemsupporting any suitable communication standards (including 5G standards)and using any suitable components, and are applicable to any radioaccess technology (RAT) or multi-RAT systems in which a UE receivesand/or transmits signals (e.g., data). For example, the variousembodiments described herein may be applicable to LTE, LTE-Advanced,NB-IoT, 5G, UMTS, HSPA, GSM, cdma2000, WCDMA, WiMax, UMB, WiFi, anothersuitable radio access technology, or any suitable combination of one ormore radio access technologies. Although certain embodiments may bedescribed in the context of wireless transmissions in the DL, thepresent disclosure contemplates that the various embodiments are equallyapplicable in the UL.

As described above, certain embodiments provide novel methods forcontrolling DRX operations in connected mode. In the followingdescription of various non-limiting example embodiments, certainassumptions can be made with respect to scheduling and HARQ operationsfor NB-IoT. First, it is assumed that DL/UL data is scheduled by amessage on the DL control channel (e.g., NB-PDCCH). Second, it isassumed that DL/UL data is transmitted on the shared channels (e.g.,NB-PDSCH and NB-PUSCH, respectively). Third, it is assumed that HARQfeedback is transmitted on the channels NB-PDCCH/NB-PUSCH (the ULresource for HARQ feedback is assumed to be sent as part of the DLassignment on NB-PDCCH). Finally, it is assumed that asynchronous HARQis used in both DL and UL. Note that the scope of the present disclosureis not limited to the various example embodiments described herein. Insome cases, none, some, or all of the above assumptions may apply.

As described above, a UE 510 may monitor a DL control channel (e.g.,NB-PDCCH). Herein, the time when UE 510 monitors the DL control channelis referred to as the “active time.” The behavior of UE 510 in relationto the start of the “active time,” stop of the “active time,” expirationof the “active time” and how to retrieve information of the length andstart of “active time” is described generally below in the context ofFIG. 5, and in detail with respect to FIGS. 6A-9B below. In certainembodiments, the start of the “active time” occurs an “offset time”after an UL transmission from UE 510.

In certain embodiments, the behavior of UE 510 is described in thecontext of NB-IoT, and when the “active time” expires UE 510 is said toenter DRX operation in a similar way as in legacy LTE (i.e., theNB-PDCCH is only monitored during an “On Duration time” every DRXcycle). Note, however, that the various embodiments described herein arenot limited to the NB-IoT context. Rather, the present disclosurecontemplates that the various embodiments described herein areapplicable to any suitable RATs.

In general, two main parameters are used: an “active time” thatdetermines for how long a time the UE should be awake to monitor the DLcontrol channel before going into DRX; and an “offset time” thatdetermines when to start the “active time.” As described above, the“offset time” (which may be referred to herein interchangeably as“offset period”) is started relative to an UL transmission performed byUE 510 that was triggered by receiving an indication of a DL or ULtransmission for UE 510 (e.g., a control message on the DL controlchannel (e.g., NB-PDCCH), such as: a DL assignment for receiving DL dataresulting in that the UL transmission is a HARQ feedback message; or anUL grant resulting in that said UL transmission is UL data).

If a new control message is received on the DL control channel duringthe “active time,” the “active time” is stopped (i.e., the UE does notneed to be awake to monitor the DL control channel (e.g., NB-PDCCH).Instead, the activity as said control message (e.g., DL-assignment orUL-grant) indicated is first performed and a new “active time” and“offset time” are used.

In certain embodiments, information about the values of the twoparameters (“active time” and “offset time”) is provided pertransmission as part of the DL-assignment/UL-grant message sent on theDL control channel, and may vary in-between everyDL-assignment/UL-grant. For example, in certain embodiments a networknode (e.g., network node 515) may determine a duration of the “activetime” and the “offset time” for use by UE 510 to control DRX operation.Network node 515 may send information about the durations of the “activetime” and the “offset time” to UE 510. Network node 515 may send theinformation to UE 510 in any suitable manner. As one example, networknode 515 may send a message to UE 510 including information about theduration of the “active time” and the “offset time.” As another example,the information about the duration of the “active time” and the “offsettime” may be included in the indication of a DL or UL transmission forUE 510 (e.g., a control message on the DL control channel (e.g,NB-PDCCH), such as: a DL assignment for receiving DL data resulting inthat the UL transmission is a HARQ feedback message; or an UL grantresulting in that said UL transmission is UL data).

Although certain example embodiments may be described in terms ofparameters described as time durations, this is for purposes of exampleonly. The various embodiments described herein are not limited to suchexamples. Rather, the present disclosure contemplates that timers may beused instead when implementing, specifying, describing, and/or modelingthese features of the various embodiments. Persons skilled in the artunderstand that descriptions using a time duration or a timer may beequivalent. In some cases, when implementing the various embodimentsdescribed herein in a device, a timer could preferably be used. In sucha scenario, UE 510 may start a timer (with duration “offset time”) afterthe UL transmission ends, and upon expiry of said timer a new timer(with duration “offset time”) may be started, and while running UE 510monitors the DL control channel (e.g., NB-PDCCH). Although the use ofmultiple timers is discussed herein, according to alternativeembodiments, fewer timers (or even no timers) may be used, as long astime duration is still monitored and determined.

For example, in certain embodiments UE 510 monitors a DL control channel(e.g., NB-PDCCH) during a duration of at least a first timer. In certainembodiments, one or more timers may be running at this time. In certainembodiments, the first timer of the one or more timers may be one of anonDurationTimer of a DRX cycle, a drx-InactivityTimer, and a DRXretransmission timer. UE 510 may receive, on the monitored DL control,an indication of a DL or UL transmission for UE 510 (e.g., a DLscheduling assignment or an UL grant, respectively). After receiving theindication of the DL or UL transmission for UE 510, UE 510 may stopmonitoring the first timer, and perform an UL transmission associatedwith the indicated DL or UL transmission for UE 510 (e.g., send an ACKmessage or a data transmission in the UL). According to certainembodiments, after receiving the indication of the DL or UL transmissionfor UE 510, UE 510 may also stop monitoring of the DL control channel.According to alternative embodiments, the UE is no longer required tomonitor the DL control channel at this point, but may continue to do so.After receiving the indication of the DL or UL transmission, UE 510starts a second timer, the duration of the second timer comprising anoffset period (e.g., a HARQ-RTT timer that comprises an offset period).According to certain embodiments, UE may start the second timer afterperforming the associated UL transmission. When the second timerexpires, UE 510 may start a third timer (e.g., a drx-InactivityTimer ora discontinuous reception retransmission timer). In certain embodiments,UE 510 may monitor the DL control channel during the duration of thethird timer, and enter DRX mode when the third timer expires.

The various embodiments will now be described in more detail below withrespect to FIGS. 6-9. Note that the time durations of the transmissionsand the offsets in-between transmissions shown in FIGS. 6-9 are not toscale and are not necessarily in a time unit such as one frame/sub-frame(e.g., 1 ms). Rather, FIGS. 6-9 are used to illustrate what istransmitted (e.g., control/data) on the different NB-IoT physicalchannels, in what order, the different channel/transmission offsets, andwhat timer durations exist. Note that the description below includesexamples of the use of both time durations and timers. To reflect thateither implementation is possible, FIGS. 6-9 illustrate a “* time(r),”an “offset time(r),” and an “active time(r).”

FIG. 6A illustrates a first example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments. Moreparticularly, FIG. 6A shows an indication of a DL transmission 605 for aUE received on downlink control channel 610 (NB-PDCCH in the example ofFIG. 6A), namely a DL scheduling assignment (denoted DCI-1 in theexample of FIG. 6A) with resulting data transmission 615. In otherwords, message 605 (denoted DCI-1) is received by the UE on DL controlchannel 610 that schedules a DL data block 615 (denoted SRB/DRB in theexample of FIG. 6A) to be received by the UE on NB-PDSCH 620 (either ona Signaling Radio Bearer (SRB) or a Data Radio Bearer (DRB)). Asdescribed above, the HARQ feedback resource for NB-PUSCH 635 is assumedto be included in the NB-PDCCH message 605 (i.e., DCI-1).

In the example of FIG. 6A, after receiving the indication of the DLtransmission 605 for the UE (i.e., when the DCI-1 is received), “* time”630 is stopped and the UE stops monitoring DL control channel 610. Thisis because DL control channel 610 does not need to be monitored anylonger due to successful reception in the UE. According to alternativeembodiments, control channel 610 may still be monitored, even though theUE is no longer required to do so. The “*” indicates that it could beeither an “On Duration” or “active” time. For example, in embodiments inwhich one or more timers are used, “* time” 630 shown in the example ofFIG. 6A may be a first timer during the duration of which the UEmonitors DL control channel 610. For example, first timer 630 may be oneof an onDurationTimer of a DRX cycle, a drx-InactivityTimer, and a DRXretransmission timer. Message 605 triggers an UL transmission activity635 later in time. In the DL assignment case shown in the example ofFIG. 6A, first SRB/DRB data 615 on NB-PDSCH 620 is received and, basedon the decoding result, the HARQ feedback is sent (ACK 635 in theexample of FIG. 6A) on NB-PUSCH 625. In other words, DCI-1 message 605is an indication of a DL transmission for the UE, and the UE performs ULtransmission 635 associated with the indicated DL transmission (namely,the sending of an acknowledgement message).

After performing associated UL transmission 635, “active time” 640 isstarted an “offset time” 645 after UL transmission 635 ends. Inembodiments in which timers are used, for example, after performingassociated UL transmission 635 (the ACK message in the example of FIG.6A), the UE starts second timer 645. The duration of second timer 645may be or comprise an offset period. For example, second timer 645 maybe a HARQ-RTT timer that comprises an offset period. When second timer645 expires, the UE starts third timer 640 corresponding to the “activetime” described above. In certain embodiments, third timer 640 may beone of a drx-InactivityTimer and a DRX retransmission timer. During the“active time” (e.g., during the duration of third timer 640), the UEmonitors DL control channel 610 (NB-PDCCH in the example of FIG. 6A). Ifno NB-PDCCH message is received before “active time” 640 ends (e.g.,before third timer 640 expires), the UE enters DRX mode 660 as shown inthe example of FIG. 6A. During DRX, the previously-described conceptsapply (i.e., the UE wakes up for a period of time 650 (“On Duration”) tomonitor DL control channel 610 (e.g., NB-PDCCH).

In the example of FIG. 6A, the arrows 655 a-d going from DCI-1 message605 are intended to illustrate that the size (e.g., duration) of “offsettime” 645 and “active time” 640 (or the duration of second timer 645 andthird timer 640 described above, respectively) is included in DCI-1message 605 (or relevant information to be able to determine the timerduration). In certain embodiments, these parameters may change betweeneach scheduled transmission (e.g., DL assignment or UL grant), allowingthe parameters to be dynamically changed for every transmission. Forexample, a network node (e.g., eNB 515 described above in relation toFIG. 5) may determine a duration of second timer 645 comprising anoffset period and third timer 640 described above for use by the UE tocontrol DRX operation. The duration of second timer 645 may be an amountof time that the UE waits after sending UL transmission 635 associatedwith the indicated DL transmission for the UE before the UE starts thirdtimer 640. The duration of third timer 640 may comprise an amount oftime that the UE monitors DL control channel 610 before entering DRXmode. The network node may send, to the UE, information about theduration of second timer 645 and third timer 640 to the UE.

The present disclosure contemplates that information about the variousparameters (e.g., length of “offset time” 645 and “active time” 640 orduration of second timer 645 and third timer 640 described above) may besignaled in any suitable manner. For example, they could be part of anL3 message or broadcasted on the system information. In such a scenario,the parameters would be semi-static as in previous approaches and not asflexible as sending them as part of the NB-PDCCH message 605 (e.g.,DCI-1 in the example of FIG. 6A). Note also that the exact value doesnot necessarily need to be signaled. Instead, a table could bebroadcasted and/or pre-defined and an index to that table could besignaled and/or included.

In the example of FIG. 6A involving a DL assignment, typical examples ofthe different time durations are given below. Note, however, that anyvalues may apply depending on, for example, the used UL/DL frequencyresources, coding rate & number of repetitions (i.e., the redundancy),message/data size, modulation type, network node (e.g., eNB) schedulingstrategy, and any other suitable criteria. In certain embodiments, theNB-PDCCH (DCI-1) duration may be 2 ms. The offset between NB-PDCCH andNB-PDSCH may be 4 ms. The NB-PDSCH (SRB/DRB) duration may be 20 ms. Theoffset between NB-PDSCH and NB-PUSCH may be 2 ms. The NB-PUSCH (ACK)duration may be 4 ms. The duration of “offset time” 645 may be 10 ms.The duration of “active time” 640 may be 20 ms.

FIG. 6B illustrates a variation of the first example of timing andtransmission for controlling DRX operations in FIG. 6A, in accordancewith certain embodiments. FIG. 6B is similar to FIG. 6A, so only thedifferences will be described. In the example embodiment of FIG. 6B,“active time” 640 is started an “offset time” 645 after the end of thereceived indication of a DL transmission 605 for the UE received on DLcontrol channel 610 (NB-PDCCH in the example of FIG. 6B), namely a DLscheduling assignment (denoted DCI-1 in the example of FIG. 6B). Inembodiments in which timers are used, for example, after the end of thereceived indication of DL transmission 605 for the UE, the UE startssecond timer 645. The duration of second timer 645 may be or comprise anoffset period. For example, second timer 645 may be a HARQ-RTT timerthat comprises an offset period. When second timer 645 expires, the UEstarts third timer 640 corresponding to the “active time.”

FIG. 7A illustrates a second example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments. Moreparticularly, FIG. 7A shows an indication of an UL transmission for theUE, namely UL grant 705 (denoted DCI-0 in the example of FIG. 7A) withresulting UL transmission 710. In other words, message 705 (denotedDCI-0) is received by the UE on DL control channel 715 (NB-PDCCH in theexample of FIG. 7A) that schedules UL data block 710 to be sent by theUE on NB-PUSCH 720 (either on an SRB or a DRB).

In the example of FIG. 7A, after receiving the indication of the ULtransmission for the UE (i.e., when DCI-0 705 is received) “* time” 725is stopped and the UE stops monitoring DL control channel 715. This isbecause DL control channel 715 (NB-PDCCH in the example of FIG. 7) doesnot need to be monitored any longer due to successful reception in theUE. According to alternative embodiments, control channel 715 may stillbe monitored, even though the UE is no longer required to do so. Similarto FIG. 6A described above, “* time” 725 indicates that it could beeither an “On Duration” or “active” time. For example, in embodiments inwhich one or more timers are used, “*time” 725 may be a first timer 725during the duration of which the UE monitors DL control channel 715. Forexample, first timer 725 may be one of an onDurationTimer of a DRXcycle, a drx-InactivityTimer, and a DRX retransmission timer. Message705 triggers an UL transmission activity 710 later in time. In the ULgrant case shown in the example of FIG. 7A, the UE performs transmissionof SRB/DRB data 710 on NB-PUSCH 720. In other words, DCI-0 message 705is an indication of an UL transmission 710 for the UE, and the UEperforms the UL transmission associated with the indication (namely,transmission of SRB/DRB data 710 on NB-PUSCH 720).

After performing associated UL transmission 710, “active time” 730 isstarted an “offset time” 735 after UL transmission 710 ends. Inembodiments in which timers are used, for example, after performingassociated UL transmission 710, the UE starts second timer 735corresponding to the “offset time” described above. The duration ofsecond timer 735 may be or comprise an offset period. For example,second timer 735 may be a HARQ-RTT timer that comprises an offsetperiod. When second timer 735 expires, the UE starts third timer 730corresponding to the “active time” described above. In certainembodiments, third timer 730 may be one of a drx-InactivityTimer and aDRX retransmission timer. During “active time” 730 (e.g., during theduration of third timer 730), the UE monitors DL control channel 715(NB-PDCCH in the example of FIG. 7A). If no NB-PDCCH message is receivedbefore “active time” 730 ends (i.e., before third timer 730 expires),the UE enters DRX mode 750 as shown in the example of FIG. 7A. DuringDRX, the previously-applied concepts apply (i.e., the UE wakes up for aperiod of time 740 (“On Duration”) to monitor DL control channel 715(e.g., NB-PDCCH).

In the example of FIG. 7A, arrows 745 a-c going from DCI-0 message 705are intended to illustrate that the size (e.g., duration) of “offsettime” 735 and “active time” 730 (or the duration of second timer 735 andthird timer 730 described above, respectively) is included in DCI-0message 705 (or relevant information to be able to determine the timerduration). In certain embodiments, these parameters may change betweeneach scheduled transmission (e.g., DL assignment or UL grant), allowingthe parameters to be dynamically changed for every transmission. Forexample, a network node (e.g., eNB 515 described above in relation toFIG. 5) may determine a duration of second timer 735 and third timer 730described above for use by the UE to control DRX operation. The durationof second timer 735 may be an amount of time that the UE waits aftersending UL transmission 710 associated with the indicated DL or ULtransmission for the UE before the UE starts third timer 730. Theduration of third timer 730 may comprise an amount of time that the UEmonitors DL control channel 715 before entering DRX mode. The networknode may send, to the UE, information about the duration of second timer735 and third timer 730 to the UE.

The present disclosure contemplates that information about the variousparameters (e.g., length of “offset time” 735 and “active time” 730 orduration of second timer 735 and third timer 730 described above) may besignaled in any suitable manner. For example, they could be part of anL3 message or broadcasted on the system information. In such a scenario,the parameters would be semi-static and not as flexible as sending themas part of the NB-PDCCH message (e.g., DCI-0 705 in the example of FIG.7A). Note also that the exact value does not necessarily need to besignaled. Instead, a table could be broadcasted and/or pre-defined andan index to that table could be signaled and/or included.

The present disclosure contemplates that the values of the variousparameters may be any suitable values. In certain embodiments, thevalues may vary based on any suitable criteria. For example, the valuesof the various parameters may depend on the used UL/DL frequencyresources, coding rate and number of repetitions (i.e., the redundancy),message/data size, modulation type, network node (e.g., eNB) schedulingstrategy, and any other suitable criteria.

FIG. 7B illustrates a variation of the second example of timing andtransmission for controlling DRX operations in FIG. 7A, in accordancewith certain embodiments. FIG. 7B is similar to FIG. 7A, so only thedifferences will be described. In the example embodiment of FIG. 7B,“active time” 730 is started an “offset time” 735 after the end of thereceived indication of an UL transmission 705 for the UE received on DLcontrol channel 715 (NB-PDCCH in the example of FIG. 7B), namely an ULgrant (denoted DCI-0 in the example of FIG. 7B). In embodiments in whichtimers are used, for example, after the end of the received indicationof UL transmission 705 for the UE, the UE starts second timer 735. Theduration of second timer 735 may be or comprise an offset period. Forexample, second timer 735 may be a HARQ-RTT timer that comprises anoffset period. When second timer 735 expires, the UE starts third timer730 corresponding to the “active time.”

FIG. 8A illustrates a third example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments. Moreparticularly, FIG. 8A illustrates a scenario in which a HARQretransmission is triggered for the DL. Similar to the example of timingand transmission for controlling DRX operations illustrated in FIG. 6A,FIG. 8A shows an indication of a DL transmission 805 for the UE, namelyDL scheduling assignment (denoted DCI-1 in the example of FIG. 8A) ondownlink control channel 810 with resulting data transmission 815. Inother words, message 805 (denoted DCI-1) received by the UE on DLcontrol channel 810 (NB-PDCCH in the example of FIG. 8A) schedules a DLdata block 815 (denoted SRB/DRB in the example of FIG. 8A) to bereceived by the UE on NB-PDSCH 820 (either on a SRB or a DRB).

In the example of FIG. 8A, upon receiving the indication of the DLtransmission 805 for the UE (i.e., when the DCI-1 805 is received), “*time” 825 is stopped and the UE stops monitoring DL control channel 810.This is because DL control channel 810 does not need to be monitored anylonger due to successful reception in the UE. According to alternativeembodiments, control channel 810 may still be monitored, even though theUE is no longer required to do so. The “* time” 825 indicates that itcould be either an “On Duration” or “active” time. For example, inembodiments in which one or more timers are used, “* time” 825 shown inthe example of FIG. 8A may be a first timer 825 during the duration ofwhich the UE monitors DL control channel 810. For example, first timer825 may be one of an onDurationTimer of a DRX cycle, adrx-InactivityTimer, and a DRX retransmission timer. Message 805triggers an UL transmission activity 830 later in time.

In the DL assignment case shown in the example of FIG. 8A, first theSRB/DRB data 815 on NB-PDSCH 820 is received and, based on the decodingresult, HARQ feedback 830 is sent (a NACK in the example of FIG. 8A). Inother words, DCI-1 message 805 is an indication of a DL transmission forthe UE, and the UE performs an UL transmission 830 associated with theindicated DL transmission. In the example of FIG. 8A, the associated ULtransmission 830 is HARQ feedback in the form of a “NACK” that triggersa HARQ re-transmission.

After performing associated UL transmission 830, “active time” 835 isstarted an “offset time” 840 after UL transmission 830 ends. Inembodiments in which timers are used, for example, after performingassociated UL transmission 830 (the NACK message in the example of FIG.8A), the UE starts second timer 840. The duration of second timer 840may be or comprise an offset period. For example, second timer 840 maybe a HARQ-RTT timer that comprises an offset period. When second timer840 expires, the UE starts third timer 835 corresponding to the “activetime” described above. In certain embodiments, third timer 835 may beone of a drx-InactivityTimer and a DRX retransmission timer. During“active time” 835 (e.g., during the duration of third timer 835), the UEmonitors DL control channel 810 (NB-PDCCH in the example of FIG. 8A). Ifno NB-PDCCH message is received before “active time” 835 ends (i.e.,before third timer 835 expires), the UE enters DRX mode. During DRX, thepreviously-applied concepts apply (i.e., the UE wakes up for a period oftime (“On Duration”) to monitor DL control channel 810 (e.g., NB-PDCCH).

In the example of FIG. 8A, however, the UE receives an indication of asecond DL transmission 845 for the UE (i.e., when the second DCI-1 845is received), “active time” 835 is stopped and the UE stops monitoringDL control channel 810. This is because DL control channel 810 (NB-PDCCHin the example of FIG. 8A) does not need to be monitored any longer dueto successful reception in the UE of second DCI-1 message 845. Secondmessage 845 triggers an UL transmission activity 850 later in time. Inthe DL assignment case shown in the example of FIG. 8A, first the secondinstance of SRB/DRB data 855 on NB-PDSCH 820 is received and, based onthe decoding result, the HARQ feedback is sent (ACK 850 in the exampleof FIG. 8A). In other words, second DCI-1 message 845 is a secondindication of a DL transmission 855 for the UE (i.e., a HARQre-transmission of the DL transmission 835), and the UE performs the ULtransmission 850 associated with the indicated DL HARQ re-transmission(namely, the sending of ACK message 850).

After performing the associated UL transmission 850, “active time” 860is started “offset time” 865 after UL transmission 850 ends. Inembodiments in which timers are used, for example, after performing theassociated UL transmission 850 (the NACK message in the example of FIG.8A), the UE starts second timer 865. The duration of second timer 865may be or comprise an offset period. For example, second timer 865 maybe a HARQ-RTT timer that comprises an offset period. When second timer865 expires, the UE starts third timer 860 corresponding to the “activetime” described above. In certain embodiments, third timer 860 may beone of a drx-InactivityTimer and a DRX retransmission timer. During“active time” 860 (e.g., during the duration of third timer 860), the UEmonitors DL control channel 810 (NB-PDCCH in the example of FIG. 8A). Ifno NB-PDCCH message is received before “active time” 860 ends (i.e.,before third timer 860 expires), the UE enters DRX mode 880 as shown inthe example of FIG. 8A. During DRX, the previously-applied conceptsapply (i.e., the UE wakes up for a period of time (“On Duration”) tomonitor DL control channel 810 (e.g., NB-PDCCH).

In the example of FIG. 8A, the arrows 870 a-d going from first DCI-1message 805 and arrows 875 a-d going from second DCI-1 message 845 areintended to illustrate that the size (e.g., duration) of “offset time”840, “active time” 835, “offset time” 865 and “active time” 860 (or, incertain embodiments, the duration of second and third timers describedabove, respectively) may be included in first DCI-1 message 805 andsecond DCI-1 message 845, respectively (or relevant information to beable to determine the timer duration). In certain embodiments, theseparameters may change between each scheduled transmission (e.g., betweenthe first DCI-1 message and the second DCI-1 message), allowing theparameters to be dynamically changed for every transmission. Thus, theduration of “offset time” 840 may be the same or different than “offsettime” 865. Similarly, the duration of “active time” 835 may be the sameor different than “active time” 860. A network node (e.g., eNB 515described above in relation to FIG. 5) may determine a duration of thesecond timers 840, 865 and the third timers 835, 860 described above foruse by the UE to control DRX operation. The durations of the secondtimers 840, 865 may be an amount of time that the UE waits after sendingthe UL transmissions 830, 850 associated with the indicated DL or ULtransmissions for the UE, respectively, before the UE starts thirdtimers 835, 860. The duration of third timers 835, 860 may comprise anamount of time that the UE monitors a DL control channel before enteringDRX mode. The network node may send, to the UE, information about theduration of second timers 840, 865 and third timers 835, 860 to the UE.In some cases, the durations may be different for the first DLtransmission associated with first DCI-1 message 805 and second DCI-1message 845. In certain embodiments, the durations may be the same. Thevarious parameters (e.g., length of “offset time” 840, 865 and “activetime” 835, 860 or the duration of second timers 840, 865 and thirdtimers 835, 860 described above) may be signaled in any suitable manner.The various examples of signaling described above with respect to FIG. 6are equally applicable to the example embodiment of FIG. 8A.

FIG. 8B illustrates a variation of the third example of timing andtransmission for controlling DRX operations in FIG. 8A, in accordancewith certain embodiments. FIG. 8B is similar to FIG. 8A, so only thedifferences will be described. In the example embodiment of FIG. 8B,“active time” 835 is started an “offset time” 840 after the end of thereceived indication of a DL transmission 805 for the UE received on DLcontrol channel 810 (NB-PDCCH in the example of FIG. 8B), namely a DLscheduling assignment (denoted DCI-1 in the example of FIG. 8B). Inembodiments in which timers are used, for example, after the end of thereceived indication of DL transmission 805 for the UE, the UE startssecond timer 840. The duration of second timer 840 may be or comprise anoffset period. For example, second timer 840 may be a HARQ-RTT timerthat comprises an offset period. When second timer 840 expires, the UEstarts third timer 835 corresponding to the “active time.”

Similar to FIG. 8A described above, in the example of FIG. 8B the UEreceives an indication of a second DL transmission 845 for the UE (i.e.,when the second DCI-1 845 is received). In such a scenario, “activetime” 835 is stopped and the UE stops monitoring DL control channel 810.In the example of FIG. 8B, however, “active time” 860 is started an“offset time” 865 at the end of the second received indication of a DLtransmission 845 for the UE received on DL control channel 810 (NB-PDCCHin the example of FIG. 8B), namely a DL scheduling assignment (denotedDCI-1 in the example of FIG. 8B). In embodiments in which timers areused, for example, after the end of the second received indication of DLtransmission 845 for the UE, the UE starts second timer 865. Theduration of second timer 865 may be or comprise an offset period. Forexample, second timer 865 may be a HARQ-RTT timer that comprises anoffset period. When second timer 865 expires, the UE starts third timer860 corresponding to the “active time.”

FIG. 9A illustrates a fourth example of timing and transmission forcontrolling DRX operations, in accordance with certain embodiments. Moreparticularly, FIG. 9 illustrates a scenario in which a HARQretransmission is triggered for the UL. Similar to FIG. 7A describedabove, the example of FIG. 9A illustrates a first indication of an ULtransmission 905 for the UE, namely an UL grant (denoted DCI-0 in theexample of FIG. 9A) with resulting UL transmission 910. In other words,first message 905 (denoted DCI-0) is received by the UE on DL controlchannel 915 (NB-PDCCH in the example of FIG. 9A) that schedules an ULdata block 910 to be sent by the UE on NB-PUSCH 920 (either on an SRB ora DRB).

In the example of FIG. 9A, upon receiving the indication of the ULtransmission 905 for the UE (i.e., when DCI-0 is received) “* time” 925is stopped and the UE stops monitoring DL control channel 915. This isbecause DL control channel 915 (NB-PDCCH in the example of FIG. 9A) doesnot need to be monitored any longer due to successful reception in theUE. According to alternative embodiments, control channel 915 may stillbe monitored, even though the UE is no longer required to do so. Similarto FIG. 7A described above, “* time” 925 indicates that it could beeither an “On Duration” or “active” time. For example, in embodiments inwhich one or more timers are used, “* time” 925 shown in the example ofFIG. 9A may be first timer 925 during the duration of which the UEmonitors DL control channel 915. For example, first timer 925 may be oneof an onDurationTimer of a DRX cycle, a drx-InactivityTimer, and a DRXretransmission timer. Message 905 triggers an UL transmission activity910 later in time. In the UL grant case shown in the example of FIG. 9A,the UE performs transmission of SRB/DRB data 910 on NB-PUSCH 920. Inother words, DCI-0 message 905 is an indication of an UL transmissionfor the UE, and the UE performs the UL transmission 910 associated withthe indicated UL transmission (namely, transmission of the SRB/DRB dataon NB-PUSCH 920).

After performing the associated UL transmission, “active time” 930 isstarted an “offset time” 935 after UL transmission 910 ends. Inembodiments in which timers are used, for example, after performing theassociated UL transmission 910 (the UL transmission on either of SRB/DRBin the example of FIG. 9A), the UE starts second timer 935. The durationof second timer 935 may be or comprise an offset period. For example,second timer 935 may be a HARQ-RTT timer that comprises an offsetperiod. When second timer 935 expires, the UE starts third timer 930corresponding to the “active time” described above. In certainembodiments, third timer 930 may be one of a drx-InactivityTimer and aDRX retransmission timer. During “active time” 930 (e.g., during theduration of third timer 930), the UE monitors DL control channel 915(NB-PDCCH in the example of FIG. 9A). If no NB-PDCCH message is receivedbefore “active time” 930 ends (e.g., before third timer 930 expires),the UE enters DRX mode.

In the UL grant case shown in the example of FIG. 9A, however, the UEreceives a second message 940 that is either a second DCI-0 message or aNACK message on DL control channel 915 before the expiration of “activetime” 930 (e.g., before the expiration of third timer 930). In scenariosin which second message 940 is a NACK message, it could be an UL grantwith the new data indicator (NDI) not toggled in case adaptive HARQretransmission is used (i.e., an implicit NACK is used). Second message940 provides an indication of a HARQ UL re-transmission 945 for the UE.Upon receiving second message 940, “active time” 930 (or, in some cases,third timer 930) is stopped and the UE stops monitoring DL controlchannel 915. This is because DL control channel 915 (NB-PDCCH in theexample of FIG. 9A) does not need to be monitored any longer due tosuccessful reception in the UE of second message 940 (either a secondDCI-0 message or a NACK). Second message 940 triggers UL transmissionactivity 945 later in time (i.e., the HARQ re-transmission of ULtransmission 910). In the UL grant case shown in the example of FIG. 9A,the UE performs second UL transmission 945 (namely, transmission ofsecond SRB/DRB data on NB-PUSCH 920).

After performing second associated UL transmission 945, “active time”950 is started “offset time” 955 after UL transmission 945 ends. Inembodiments in which timers are used, for example, after performingsecond associated UL transmission 945 (transmission of second SRB/DRBdata on NB-PUSCH 920 in the example of FIG. 9A), the UE starts secondtimer 955. The duration of second timer 955 may be or comprise an offsetperiod. For example, second timer 955 may be a HARQ-RTT timer thatcomprises an offset period. When second timer 955 expires, the UE startsthird timer 950 corresponding to the “active time” described above. Incertain embodiments, third timer 950 may be one of a drx-InactivityTimerand a DRX retransmission timer. During “active time” 950 (e.g., duringthe duration of third timer 950), the UE monitors DL control channel 915(NB-PDCCH in the example of FIG. 9A). If no NB-PDCCH message is receivedbefore “active time” 950 ends (e.g., before third timer 950 expires),the UE enters DRX mode 970 as shown in the example of FIG. 9A. DuringDRX, the previously-applied concepts apply (i.e., the UE wakes up for aperiod of time (“On Duration”) to monitor DL control channel 915 (e.g.,NB-PDCCH).

In the example of FIG. 9A, arrows 960 a-c going from first DCI-0 message905 and arrows 965 a-c going from second DCI-0 message 905 are intendedto illustrate that the size (e.g., duration) of “offset time” 935,“active time” 930, “offset time” 955 and “active time” 950 (or, incertain embodiments, the duration of second timers 935, 955 and thirdtimers 930, 950 described above, respectively) may be included in firstDCI-0 message 905 and second DCI-0 message 940, respectively (orrelevant information to be able to determine the timer duration). Incertain embodiments, these parameters may change between each scheduledtransmission (e.g., between first DCI-0 message 905 and second DCI-0message 940), allowing the parameters to be dynamically changed forevery transmission. Thus, the duration of “offset time” 935 may be thesame or different than “offset time” 955. Similarly, the duration of“active time” 930 may be the same or different than “active time” 950. Anetwork node (e.g., eNB 515 described above in relation to FIG. 5) maydetermine a duration of second timers 935, 955 and third timers 930, 950described above for use by the UE to control DRX operation. Thedurations of second timers 935, 955 may be an amount of time that the UEwaits after sending the UL transmissions 910, 945 associated with theindicated UL transmissions for the UE, respectively, before the UEstarts third timers 930, 950. The duration of third timers 930, 950 maycomprise an amount of time that the UE monitors DL control channel 915before entering DRX mode. The network node may send, to the UE,information about the duration of second timers 935, 955 and thirdtimers 930, 950 to the UE. In some cases, the durations may be differentfor the first UL transmission associated with first DCI-0 message 905and second DCI-0 message 940. In certain embodiments, the durations maybe the same. The various parameters (e.g., length of “offset time” 935,955 and “active time” 930, 950 or the duration of second timers 935, 955and third timers 930, 950 described above) may be signaled in anysuitable manner. The various examples of signaling described above withrespect to FIG. 6A are equally applicable to the example embodiment ofFIG. 9A.

The present disclosure contemplates that the values of the variousparameters may be any suitable values. In certain embodiments, thevalues may vary based on any suitable criteria. For example, the valuesof the various parameters may depend on the used UL/DL frequencyresources, coding rate and number of repetitions (i.e., the redundancy),message/data size, modulation type, network node (e.g., eNB) schedulingstrategy, and any other suitable criteria.

FIG. 9B illustrates a variation of the fourth example of timing andtransmission for controlling DRX operations in FIG. 9A, in accordancewith certain embodiments. FIG. 9B is similar to FIG. 9A, so only thedifferences will be described. In the example embodiment of FIG. 9B,“active time” 930 is started an “offset time” 935 after the end of thereceived indication of an UL transmission 905 for the UE received on DLcontrol channel 915 (NB-PDCCH in the example of FIG. 9B), namely an ULgrant (denoted DCI-0 in the example of FIG. 9B). In embodiments in whichtimers are used, for example, after the end of the received indicationof UL transmission 905 for the UE, the UE starts second timer 935. Theduration of second timer 935 may be or comprise an offset period. Forexample, second timer 935 may be a HARQ-RTT timer that comprises anoffset period. When second timer 935 expires, the UE starts third timer930 corresponding to the “active time.”

Similar to FIG. 9A described above, in the example of FIG. 9B the UEreceives a second message 940 that is either a second DCI-0 message or aNACK message on DL control channel 915 before the expiration of “activetime” 930 (e.g., before the expiration of third timer 930). Secondmessage 940 provides an indication of a second UL transmission 945 forthe UE. Upon receiving second message 940, “active time” 930 (or, insome cases, third timer 930) is stopped and the UE stops monitoring DLcontrol channel 915. In the example of FIG. 9B, however, “active time”950 is started an “offset time” 955 after the end of the second receivedindication of an UL transmission 940 for the UE received on DL controlchannel 915 (NB-PDCCH in the example of FIG. 9B). In embodiments inwhich timers are used, for example, at the end of the second receivedindication of an UL transmission 940 for the UE, the UE starts secondtimer 955. The duration of second timer 955 may be or comprise an offsetperiod. For example, second timer 955 may be a HARQ-RTT timer thatcomprises an offset period. When second timer 955 expires, the UE startsthird timer 950 corresponding to the “active time.”

Although the example embodiments of FIGS. 6A-9B describe DL assignmentsand UL grants as example of stop criteria, the present disclosure is notlimited to these examples. Rather, the present disclosure contemplatesthe use of alternative stop criteria for the “active time,” for exampleby sending other messages defined on the NB-PDCCH that is not a DLassignment or an UL grant. Such a message could, for example, be an“order” to enter DRX directly (applying the OnDuration/DRX-cycle).Another example could be to send new “offset time”/“active time”parameters to postpone the “active time” an “offset time” relative tothe received NB-PDCCH message. This could be done to indicate to the UEthat it temporarily cannot be served (e.g., due to too many UEscurrently being served).

FIG. 10 is a flow chart of an example of DRX operations, in accordancewith certain embodiments. At step 1005, the UE monitors the DL controlchannel (e.g., NB-PDCCH) during OnDuration Time or Active Time. If atstep 1010 either the On Duration Time or Active Time expires, the flowproceeds to step 1015 and the UE enters DRX mode and waits for the nextOnDuration occurrence. During the time the UE waits for the nextOnDuration occurrence, the UE does not monitor the DL control channel.At step 1020, the next OnDuration occurrence occurs. At step 1025, theUE starts the OnDuration timer. Once the OnDuration timer is started,the flow returns to step 1005 and the UE monitors the downlink controlchannel (e.g., NB-PDCCH) during the OnDuration Time or Active Time.

Alternatively, during monitoring of NB-PDCCH at step 1005 the flow mayproceed to step 1030 if the UE receives a message on the downlinkcontrol channel (e.g., a DL scheduling assignment or an UL grant).

In some cases, at step 1035 the NB-PDCCH message received at step 1030may be a DRX order. In such a scenario, the flow proceeds to step 1015,where the UE enters DRX and waits for the next OnDuration occurrence.From there, the DRX operations proceed as described above.

In some cases, at step 1040 the UE determines the content of the messagereceived on the downlink control channel. If at step 1040 the UEdetermines that the received message is an UL grant, the flow proceedsto step 1045 where the UE transmits UL SRB and/or DRB data on an ULshared channel (NB-PUSCH in the example of FIG. 10). Alternatively, atstep 1040 the UE may determine that the received message is a DLscheduling assignment. In such a scenario, the flow proceeds to step1050 where the UE receives and decodes SRB and/or DRB data on a DLshared channel (NB-PDSCH in the example of FIG. 10). At step 1055, theUE transmits HARQ feedback on the UL shared channel (e.g., NB-PUSCH). Incertain embodiments, for example, the HARQ feedback may be an ACKmessage or a NACK message.

The flow then proceeds to step 1060, where the UE waits for an “offsettime.” In certain embodiments, the UE may start a timer. In certainembodiments, the timer may be started either after performing theassociated UL transmission (for example, when the UE determines that thereceived message is an UL grant) or at the end of the receivedindication of the DL or UL transmission for the UE (for example, whenthe UE determines that the received message is a DL schedulingassignment). Thus, the duration of the timer may comprise an amount oftime that the UE waits after sending the UL transmission at step 1045before the UE starts an “active time” or an amount of time that the UEwaits after the end of the indication of the DL or UL transmission atstep 1030 before the UE starts an “active time.” After waiting for the“offset time” at step 1060 (or, in certain embodiments, the timer havingthe duration of the offset time expires), the flow proceeds to step1065. At step 1065, the UE starts the active time. In certainembodiments, the UE may start another timer having a duration that is anamount of time that the UE monitors the DL control channel (e.g.,NB-PDCCH) before the UE enters DRX mode. After starting the active timeat step 1065, the flow returns to step 1005, where the UE monitorsNB-PDCCH during the duration of the “active time.”

FIG. 11 is a flow diagram of a method 1100 in a UE, in accordance withcertain embodiments. The method begins at step 1104, where the UEmonitors a DL control channel during a duration of at least a firsttimer. In certain embodiments, the first timer may be an onDurationTimerof a discontinuous reception cycle. In certain embodiments, the firsttimer may be a drx-InactivityTimer. In certain embodiments, the firsttimer may be a discontinuous reception retransmission timer.

At step 1108, the UE receives, on the monitored DL control channel, anindication of a DL or UL transmission for the UE. In certainembodiments, the indication of the DL or UL transmission for the UE maycomprise information about a duration of at least one of the second andthird timers. At step 1112, after receiving the indication of the DL orUL transmission for the UE, the UE stops monitoring the first timer.After the first timer is stopped, the UE does not need to monitor thedownlink control channel.

At step 1116, the UE performs an UL transmission associated with theindicated DL or UL transmission for the UE. In certain embodiments, theindication of the DL or UL transmission for the UE may comprise a DLscheduling assignment, and the UL transmission associated with theindicated DL transmission may comprise an acknowledgement message. Incertain embodiments, the indication of the DL or UL transmission for theUE may comprise an UL grant, and the UL transmission associated with theindicated UL transmission may comprise a data transmission in the UL.

At step 1120, the UE starts a second timer after receiving theindication for the downlink or uplink transmission for the UE, theduration of the second timer comprising an offset period. In certainembodiments, the second timer may be started either: after performingthe associated UL transmission; or at the end of the received indicationof the DL or UL transmission for the UE. In certain embodiments, thesecond timer may be a Hybrid Automatic Repeat reQuest (HARQ)-Round TripTime (RTT) timer that comprises the offset period. Alternatively, atstep 1120, the UE starts a second timer after receiving the indicationfor the downlink or uplink transmission for the UE.

At step 1124, when the second timer expires, the UE starts a thirdtimer. In certain embodiments, the method may comprise monitoring the DLcontrol channel during the duration of the third timer. In certainembodiments, at least one of the first timer and the third timer may bea drx-InactivityTimer. In certain embodiments, at least one of the firsttimer and the third timer may be a discontinuous receptionretransmission timer.

In certain embodiments, the method may comprise entering a discontinuousreception mode when the third timer expires. In certain embodiments, themethod may comprise receiving a message including information about aduration of at least one of the second and third timers.

FIG. 12 is a flow diagram of a method 1200 in a network node, inaccordance with certain embodiments. The method begins at step 1204,where the network node determines a duration of a first timer and aduration of a second timer, the first and second timers for use by a UEto control discontinuous reception operation, wherein the duration ofthe first timer comprises an offset period. In certain embodiments, theduration of the first timer may comprise one of: an amount of time thatthe UE waits after sending the UL transmission associated with theindicated DL or UL transmission for the UE before the UE starts thesecond timer; and an amount of time that the UE waits after the end ofthe indication of the DL or UL transmission for the UE before the UEstarts the second timer. In certain embodiments, the first timer may bea Hybrid Automatic Repeat reQuest (HARQ)-Round Trip Time (RTT) timer. Incertain embodiments, the duration of the second timer may comprise anamount of time that the UE monitors a DL control channel before enteringa discontinuous reception mode. In certain embodiments, the second timermay be a drx-InactivityTimer. In certain embodiments, the second timermay be a discontinuous reception retransmission timer.

At step 1208, the network node sends, to the UE, information about theduration of the first timer and the duration of the second timer. Incertain embodiments, the information about the duration of the firsttimer and the duration of the second timer may be included in anindication of a DL or UL transmission for the UE. In certainembodiments, sending, to the UE, information about the duration of thefirst timer and the duration of the second timer may comprises sending amessage to the UE including the information about the duration of thefirst timer and the duration of the second timer.

In certain embodiments, the method may comprise sending, to the UE, anindication of a DL or UL transmission for the UE, and receiving, fromthe UE, an UL transmission associated with the indicated DL or ULtransmission for the UE. In certain embodiments, the indication of theDL or UL transmission for the UE may comprise a DL schedulingassignment, and the UL transmission associated with the indicated DLtransmission may comprise an acknowledgement message. In certainembodiments, the indication of the DL or UL transmission for the UE maycomprise an UL grant, and the UL transmission associated with theindicated UL transmission may comprise a data transmission in the UL.According to certain embodiments, the network node may transmit downlinkcontrol messages during the duration of the third timer. This may bebeneficial when the UE stops monitoring the downlink control channelafter a first timer is stopped.

FIG. 13 is a block schematic of an exemplary UE, in accordance withcertain embodiments. UE 510 may refer to any type of wireless devicecommunicating with a node and/or with another wireless device in acellular or mobile communication system. Examples of UE 510 include amobile phone, a smart phone, a PDA (Personal Digital Assistant), aportable computer (e.g., laptop, tablet), a sensor, a modem, amachine-type-communication (MTC) device/machine-to-machine (M2M) device,laptop embedded equipment (LEE), laptop mounted equipment (LME), USBdongles, a D2D capable device, or another device that can providewireless communication. UE 510 may also be referred to as wirelessdevice, a station (STA), a device, or a terminal in some embodiments. UE510 includes transceiver 1310, processing circuitry 1320, and memory1330. In some embodiments, transceiver 1310 facilitates transmittingwireless signals to and receiving wireless signals from network node 515(e.g., via antenna 1340), processing circuitry 1320 executesinstructions to provide some or all of the functionality described aboveas being provided by UE 510, and memory 1330 stores the instructionsexecuted by processing circuitry 1320.

Processing circuitry 1320 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of UE 510, such as the functions of UE 510 described above inrelation to FIGS. 1-12. In some embodiments, processing circuitry 1320may include, for example, one or more computers, one or more centralprocessing units (CPUs), one or more microprocessors, one or moreapplications, one or more application specific integrated circuits(ASICs), one or more field programmable gate arrays (FPGAs) and/or otherlogic.

Memory 1330 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processing circuitry 1320. Examples ofmemory 1330 include computer memory (for example, Random Access Memory(RAM) or Read Only Memory (ROM)), mass storage media (for example, ahard disk), removable storage media (for example, a Compact Disk (CD) ora Digital Video Disk (DVD)), and/or or any other volatile ornon-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information, data, and/orinstructions that may be used by processing circuitry 1320.

Other embodiments of UE 510 may include additional components beyondthose shown in FIG. 13 that may be responsible for providing certainaspects of the UE's functionality, including any of the functionalitydescribed above and/or any additional functionality (including anyfunctionality necessary to support the solution described above). Asjust one example, UE 510 may include input devices and circuits, outputdevices, and one or more synchronization units or circuits, which may bepart of the processing circuitry 1320. Input devices include mechanismsfor entry of data into UE 510. For example, input devices may includeinput mechanisms, such as a microphone, input elements, a display, etc.Output devices may include mechanisms for outputting data in audio,video and/or hard copy format. For example, output devices may include aspeaker, a display, etc.

FIG. 14 is a block schematic of an exemplary network node, in accordancewith certain embodiments. Network node 515 may be any type of radionetwork node or any network node that communicates with a UE and/or withanother network node. Examples of network node 515 include an eNodeB, anode B, a base station, a wireless access point (e.g., a Wi-Fi accesspoint), a low power node, a base transceiver station (BTS), relay, donornode controlling relay, transmission points, transmission nodes, remoteRF unit (RRU), remote radio head (RRH), multi-standard radio (MSR) radionode such as MSR BS, nodes in distributed antenna system (DAS), O&M,OSS, SON, positioning node (e.g., E-SMLC), MDT, or any other suitablenetwork node. Network nodes 515 may be deployed throughout network 500as a homogenous deployment, heterogeneous deployment, or mixeddeployment. A homogeneous deployment may generally describe a deploymentmade up of the same (or similar) type of network nodes 515 and/orsimilar coverage and cell sizes and inter-site distances. Aheterogeneous deployment may generally describe deployments using avariety of types of network nodes 515 having different cell sizes,transmit powers, capacities, and inter-site distances. For example, aheterogeneous deployment may include a plurality of low-power nodesplaced throughout a macro-cell layout. Mixed deployments may include amix of homogenous portions and heterogeneous portions.

Network node 515 may include one or more of transceiver 1410, processingcircuitry 1420, memory 1430, and network interface 1440. In someembodiments, transceiver 1410 facilitates transmitting wireless signalsto and receiving wireless signals from UE 510 (e.g., via antenna 1450),processing circuitry 1420 executes instructions to provide some or allof the functionality described above as being provided by a network node515, memory 1430 stores the instructions executed by processingcircuitry 1420, and network interface 1440 communicates signals tobackend network components, such as a gateway, switch, router, Internet,Public Switched Telephone Network (PSTN), core network nodes or radionetwork controllers 130, etc.

Processing circuitry 1420 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of network node 515, such as those described above in relationto FIGS. 1-12 above. In some embodiments, processing circuitry 1420 mayinclude, for example, one or more computers, one or more centralprocessing units (CPUs), one or more microprocessors, one or moreapplications, and/or other logic.

Memory 1430 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by processing circuitry 1420. Examples ofmemory 1430 include computer memory (for example, Random Access Memory(RAM) or Read Only Memory (ROM)), mass storage media (for example, ahard disk), removable storage media (for example, a Compact Disk (CD) ora Digital Video Disk (DVD)), and/or or any other volatile ornon-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information.

In some embodiments, network interface 1440 is communicatively coupledto processing circuitry 1420 and may refer to any suitable deviceoperable to receive input for network node 515, send output from networknode 515, perform suitable processing of the input or output or both,communicate to other devices, or any combination of the preceding.Network interface 1440 may include appropriate hardware (e.g., port,modem, network interface card, etc.) and software, including protocolconversion and data processing capabilities, to communicate through anetwork.

Other embodiments of network node 515 may include additional componentsbeyond those shown in FIG. 14 that may be responsible for providingcertain aspects of the radio network node's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). The various different types of network nodes mayinclude components having the same physical hardware but configured(e.g., via programming) to support different radio access technologies,or may represent partly or entirely different physical components.

FIG. 15 is a block schematic of an exemplary radio network controller orcore network node 130, in accordance with certain embodiments. Examplesof network nodes can include a mobile switching center (MSC), a servingGPRS support node (SGSN), a mobility management entity (MME), a radionetwork controller (RNC), a base station controller (BSC), and so on.The radio network controller or core network node 130 includesprocessing circuitry 1520, memory 1530, and network interface 1540. Insome embodiments, processing circuitry 1520 executes instructions toprovide some or all of the functionality described above as beingprovided by the network node, memory 1530 stores the instructionsexecuted by processing circuitry 1520, and network interface 1540communicates signals to any suitable node, such as a gateway, switch,router, Internet, Public Switched Telephone Network (PSTN), networknodes 515, radio network controllers or core network nodes 130, etc.

Processing circuitry 1520 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of the radio network controller or core network node 130. Insome embodiments, processing circuitry 1520 may include, for example,one or more computers, one or more central processing units (CPUs), oneor more microprocessors, one or more applications, and/or other logic.

Memory 1530 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by processing circuitry 1520. Examples ofmemory 1530 include computer memory (for example, Random Access Memory(RAM) or Read Only Memory (ROM)), mass storage media (for example, ahard disk), removable storage media (for example, a Compact Disk (CD) ora Digital Video Disk (DVD)), and/or or any other volatile ornon-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information.

In some embodiments, network interface 1540 is communicatively coupledto processing circuitry 1520 and may refer to any suitable deviceoperable to receive input for the network node, send output from thenetwork node, perform suitable processing of the input or output orboth, communicate to other devices, or any combination of the preceding.Network interface 1540 may include appropriate hardware (e.g., port,modem, network interface card, etc.) and software, including protocolconversion and data processing capabilities, to communicate through anetwork.

Other embodiments of the network node may include additional componentsbeyond those shown in FIG. 15 that may be responsible for providingcertain aspects of the network node's functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the solution describedabove).

FIG. 16 is a block schematic of an exemplary UE, in accordance withcertain embodiments. UE 510 may include one or more modules. Forexample, UE 510 may include a determining module 1610, a communicationmodule 1320, a receiving module 1630, an input module 1640, a displaymodule 1650, and any other suitable modules. In some embodiments, one ormore of determining module 1610, communication module 1620, receivingmodule 1630, input module 1640, display module 1650, or any othersuitable module may be implemented using processing circuitry, such assuch as processing circuitry 1420 described above in relation to FIG.14. In certain embodiments, the functions of two or more of the variousmodules may be combined into a single module. UE 510 may perform themethods for controlling connected mode DRX operations described abovewith respect to FIGS. 1-12.

Determining module 1610 may perform the processing functions of UE 510.For example, determining module 1610 may monitor a DL control channelduring a duration of at least a first timer. As another example,determining module 1610 may, after receiving the indication of the DL orUL transmission for the UE, stop monitoring the first timer. After thefirst timer is stopped, the UE does not need to monitor the downlinkcontrol channel. As still another example, determining module 1610 maystart a second timer after receiving the indication for the downlink oruplink transmission for the UE, the duration of the second timercomprising an offset period. As yet another example, determining module1610 may, when the second timer expires, start a third timer. As anotherexample, determining module 1610 may monitor the DL control channelduring the duration of the third timer. As another example, determiningmodule 1610 may enter a discontinuous reception mode when the thirdtimer expires.

Determining module 1610 may include or be included in one or moreprocessors, such as processing circuitry 1320 described above inrelation to FIG. 13. Determining module 1610 may include analog and/ordigital circuitry configured to perform any of the functions ofdetermining module 1610 and/or processing circuitry 1320 describedabove. The functions of determining module 1610 described above may, incertain embodiments, be performed in one or more distinct modules.

Communication module 1620 may perform the transmission functions of UE510. For example, communication module 1620 may perform an ULtransmission associated with the indicated DL or UL transmission for theUE. Communication module 1620 may transmit messages to one or more ofnetwork nodes 515 of network 500. Communication module 1620 may includea transmitter and/or a transceiver, such as transceiver 1310 describedabove in relation to FIG. 13. Communication module 1620 may includecircuitry configured to wirelessly transmit messages and/or signals. Inparticular embodiments, communication module 1620 may receive messagesand/or signals for transmission from determining module 1610. In certainembodiments, the functions of communication module 1620 described abovemay be performed in one or more distinct modules.

Receiving module 1630 may perform the receiving functions of UE 510. Asone example, receiving module 1630 may receive, on the monitored DLcontrol channel, an indication of a DL or UL transmission for the UE. Asanother example, receiving module 1630 may receive a message includinginformation about a duration of at least one of the second and thirdtimers. Receiving module 1630 may include a receiver and/or atransceiver, such as transceiver 1310 described above in relation toFIG. 13. Receiving module 1630 may include circuitry configured towirelessly receive messages and/or signals. In particular embodiments,receiving module 1630 may communicate received messages and/or signalsto determining module 1610. The functions of receiving module 1630described above may, in certain embodiments, be performed in one or moredistinct modules.

Input module 1640 may receive user input intended for UE 510. Forexample, the input module may receive key presses, button presses,touches, swipes, audio signals, video signals, and/or any otherappropriate signals. The input module may include one or more keys,buttons, levers, switches, touchscreens, microphones, and/or cameras.The input module may communicate received signals to determining module1610. The functions of input module 1640 described above may, in certainembodiments, be performed in one or more distinct modules.

Display module 1650 may present signals on a display of UE 510. Displaymodule 1650 may include the display and/or any appropriate circuitry andhardware configured to present signals on the display. Display module1650 may receive signals to present on the display from determiningmodule 1610. The functions of display module 1650 described above may,in certain embodiments, be performed in one or more distinct modules.

Determining module 1610, communication module 1620, receiving module1630, input module 1640, and display module 1650 may include anysuitable configuration of hardware and/or software. UE 510 may includeadditional modules beyond those shown in FIG. 16 that may be responsiblefor providing any suitable functionality, including any of thefunctionality described above and/or any additional functionality(including any functionality necessary to support the various solutionsdescribed herein).

FIG. 17 is a block schematic of an exemplary network node 515, inaccordance with certain embodiments. Network node 515 may include one ormore modules. For example, network node 515 may include determiningmodule 1710, communication module 1720, receiving module 1730, and anyother suitable modules. In some embodiments, one or more of determiningmodule 1710, communication module 1720, receiving module 1730, or anyother suitable module may be implemented using one or more processors,such as processing circuitry 1420 described above in relation to FIG.15. In certain embodiments, the functions of two or more of the variousmodules may be combined into a single module. Network node 515 mayperform the methods for controlling connected mode DRX operationsdescribed above with respect to FIGS. 1-12.

Determining module 1710 may perform the processing functions of networknode 515. For example, determining module 1710 may determine a durationof a first timer and a duration of a second timer, the first and secondtimers for use by a UE to control discontinuous reception operation,wherein the duration of the first timer comprises an offset period.Determining module 1710 may include or be included in one or moreprocessors, such as processing circuitry 1420 described above inrelation to FIG. 14. Determining module 1710 may include analog and/ordigital circuitry configured to perform any of the functions ofdetermining module 1710 and/or processing circuitry 1420 describedabove. The functions of determining module 1710 may, in certainembodiments, be performed in one or more distinct modules.

Communication module 1720 may perform the transmission functions ofnetwork node 515. As one example, communication module 1720 may send, tothe UE, information about the duration of the first timer and theduration of the second timer. As another example, communication module1720 may send a message to the UE including the information about theduration of the first timer and the duration of the second timer. Asstill another example, communication module 1720 may send, to the UE, anindication of a DL or UL transmission for the UE. Communication module1720 may transmit messages to one or more of UEs 510. Communicationmodule 1720 may include a transmitter and/or a transceiver, such astransceiver 1410 described above in relation to FIG. 14. Communicationmodule 1720 may include circuitry configured to wirelessly transmitmessages and/or signals. In particular embodiments, communication module1720 may receive messages and/or signals for transmission fromdetermining module 1710 or any other module. The functions ofcommunication module 1720 may, in certain embodiments, be performed inone or more distinct modules.

Receiving module 1730 may perform the receiving functions of networknode 515. For example, receiving module 1730 may receive, from the UE,an UL transmission associated with the indicated DL or UL transmissionfor the UE. Receiving module 1730 may receive any suitable informationfrom a UE. Receiving module 1730 may include a receiver and/or atransceiver, such as transceiver 1410 described above in relation toFIG. 14. Receiving module 1730 may include circuitry configured towirelessly receive messages and/or signals. In particular embodiments,receiving module 1730 may communicate received messages and/or signalsto determining module 1710 or any other suitable module. The functionsof receiving module 1730 may, in certain embodiments, be performed inone or more distinct modules.

Determining module 1710, communication module 1720, and receiving module1730 may include any suitable configuration of hardware and/or software.Network node 515 may include additional modules beyond those shown inFIG. 17 that may be responsible for providing any suitablefunctionality, including any of the functionality described above and/orany additional functionality (including any functionality necessary tosupport the various solutions described herein).

The following text provides additional explanation regarding certainembodiments and proposals described herein, and should not be seen aslimiting the scope of the invention. The functionality for connectedmode DRX in legacy LTE and eMTC are based on the following parameters(excluding the short DRX parameters):

-   -   onDurationTimer    -   drxStartOffset (signaled as longDRX-CycleStartOffset in 36.331)    -   longDRX-Cycle (signaled as longDRX-CycleStartOffset in 36.331)    -   drx-InactivityTimer    -   HARQ-RTT-Timer    -   drx-RetransmissionTimer

The first three parameters can be re-used as is for NB-IoT except forthe value ranges that need to be looked into further. The two lastparameters are related to how the HARQ operation works. Thedrx-InactivityTimer parameter is used to control when the UE enters DRXafter inactivity (unless a MAC CE is signaled) so the handling of thisparameter will mainly be discussed. As it is already decided to supportonly one HARQ process per direction and if half-duplex operation for theUE is assumed changes/simplifications to these three last parameterscould be discussed and made even if the details of the HARQ operationsare not fully decided yet.

Due to the NB-IoT UE transmission/reception capabilities beinghalf-duplex and having only one HARQ process per direction the handlingof the DRX in-activity timer and the HARQ re-transmission timers for theconnected mode DRX could be changed/simplified. Therefore, according tocertain embodiments, the legacy parameters drxStartOffset, longDRX-Cycleand OnDurationTimer may be re-used as is for connected mode DRX withvalue ranges suitable for NB-IoT.

In the following examples it is assumed that the high level concept forHARQ operations for NB-IoT is similar to eMTC. To summarize thefollowing is assumed:

-   -   Downlink/uplink data is scheduled by a message on the downlink        control channel NB-PDCCH.    -   Downlink/uplink data is transmitted on the shared channels        NB-PDSCH and NB-PUSCH respectively.    -   HARQ feedback is transmitted on the channels NB-PDCCH/NB-PUSCH.    -   Asynchronous HARQ is used in both downlink and uplink.

In the upcoming embodiments the DRX operations are explained by applyingthese HARQ assumptions. Note that the time durations of thetransmissions and the offsets in-between transmissions can vary inlength. According to one embodiment, we have used the legacy behaviorfor the DRX operation with the drx-InactivityTimer and applied it toNB-IoT. The timer is started every time there is a new transmissionscheduled either in the UL or the DL on the NB-PDCCH. In this case thedownlink transmission is successful and no further data is scheduled sothe UE goes into DRX sleep at timer expiry.

According to another embodiment there is one HARQ retransmission in thedownlink when using the legacy DRX timers in NB-IoT. The timersHARQ-RTT-Timer/drx-RetransmissionTimer are used for this and the latteris cancelled when the re-transmission is received.

Compared to legacy LTE the uplink HARQ for eMTC (and LAA) has beenchanged from synchronous to asynchronous. It is assumed here that thereis probably a need to introduce something similar as theHARQ-RTT-Timer/drx-RetransmissionTimer also for the uplink due to theasynchronous HARQ. For NB-IoT it is assumed that such timers will beneeded when discussing the legacy base for DRX. Thus, according toanother embodiment, there is a HARQ retransmission in the uplink withassumed new timer. Similar to the downlink case the timer is cancelledwhen the UE detects that a re-transmission is scheduled. Note that wecall it the drx-RetransmissionTimer even if it is not really a“Retransmission Timer” as the UE does not know the result of thetransmission. This may also be referred to as aHARQ-FeedbackWindowTimer.

As discussed, the legacy DRX timers could be used also for NB-IoT. Thislegacy scheme was developed with Mobile Broadband use cases in mind thatinclude multiple HARQ processes in both directions and full duplexoperations (except for TDD of course). For these use cases (except forVoLTE) the UE power consumption with regards to being awake a few extrasub-frames here and there is not a problem. However, for NB-IoT it isvery important that the UE active time (i.e. when monitoring NB-PDCCH)is as small as possible also during connected mode for many of its usecases in order to get a good UE battery lifetime.

One problem with the legacy approach is how to set the value of thedrx-InactivityTimer:

-   -   a short value: This is good for the UE power consumption but        will introduce additional latency in case there are DL HARQ        re-transmissions since the timer has (probably) expired at the        time the re-transmission finished and then new data must wait        for the next OnDuration occasion. A drawback with introducing        this additional latency is that the UE needs to be in connected        mode during longer time. Additionally, long time spent in        connected mode (especially if long DRX cycles are also used)        might lead to risk of larger channel variations and loss of        synchronization.    -   a long value: This is not good for the UE power consumption but        does not introduce additional latency so it will be possible to        schedule the UE faster in order for it to enter idle mode        faster.

According to particular embodiments, a solution to the above problemwould be to change drx-InactivityTimer so that it is re-started at everyNB-PDCCH reception, i.e. regardless of if it is a new transmission or are-transmission (both uplink and downlink). Then a short value of thedrx-InactivityTimer could be used at the same time as no extra latencyis introduced. If this is done then there is no need for anyHARQ-RTT-Timer/drx-RetransmissionTimer as only one timer could be usedto supervise both UL/DL re-transmissions and inactivity. This alsodecreases the UE complexity as only one timer is needed. According tothis embodiment, the drx-InactivityTimer is re-started at the receptionof any DCI on the NB-PDCCH.

According to additional embodiments, there is no need for the timersHARQ-RTT-Timer and drx-RetransmissionTimer for neither downlink noruplink if the criterion for starting the timer drx-InactivityTimer ischanged. A successful NB-PDCCH reception in the UE will be followed byan uplink transmission that contains of either SRB/DRB data (in case ofan UL grant) or HARQ feedback (in case of a DL assignment). If it isassumed that a UE is not required to monitor the NB-PDCCH after beingscheduled until after the transmission then additional changes to thestart/re-start of the drx-InactivityTimer could be made. The timershould then be stopped at every successful reception of NB-PDCCH and bestarted after the end of the uplink transmission that was triggered bythe NB-PDCCH message. This will enable the UE to be able to turn off itsreceiver (and potentially enter sleep mode) during more time occasionsin connected mode especially if the time gaps in-betweenNB-PDCCH/NB-PDSCH/NB-PUSCH are long.

According to additional embodiments, stopping the drx-InactivityTimer atsuccessful reception of anything on NB-PDCCH and starting it after theresulting uplink transmission (of DRB/SRB or HARQ feedback) enables theUE to reduce NB-PDCCH monitoring time and thus power consumption. Thus,according to certain embodiments, the start and stop criterion for thedrx-InactivityTimer is changed for NB-IoT UEs to control connected modeDRX. According to certain embodiments, the start criterion ofdrx-InactivityTimer should be changed to after the NB-PUSCH transmissionof the HARQ ACK or the DRB/SRB data for a downlink assignment and anuplink grant respectively. According to certain embodiments, the stopcriterion of drx-InactivityTimer should be changed to when a downlinkassignment or an uplink grant is received. According to certainembodiments, the HARQ-RTT-Timer and the drx-RetransmissionTimer may notbe used in NB-IoT. According to certain embodiments, if thedrx-InactivityTimer expires the UE does not need to monitor the NB-PDCCHuntil the next OnDuration occasion.

The majority of the NB-IoT use cases does not include simultaneousuplink/downlink traffic and instead most use cases rely on arequest-response type of traffic pattern where an IP packet is sent inone direction followed by a response in the other (potentially repeatedaccording to the same pattern a few times for some use cases). Thistraffic pattern is also true for the L3 (NAS/RRC) signaling procedures.As a consequence, after HARQ feedback or SRB/DRB data has beentransmitted in the uplink by a UE there will not be any NB-PDCCHactivity during at least one HARQ round trip time. During this time aNB-IoT UE could be allowed to not monitor the NB-PDCCH. Thus, accordingto certain embodiments, a change to the drx-InactivityTimer handlingwould be to not start it until an offset value after the uplinktransmission.

In most use cases there is no need for a UE to monitor the NB-PDCCHuntil at least one roundtrip time after the end of the uplinktransmission. Thus, according to certain embodiments, the start of thedrx-InactivityTimer should be made at an offset value after the uplinktransmission (of DRB/SRB or HARQ feedback) to enable the UE to reduceNB-PDCCH monitoring time. The value of this offset depends as describedabove on the roundtrip time but also on the physical layer design of theNB-PDCCH, e.g. time alignments and how the NB-PDCCH and NB-PDSCH ismultiplexed. The value may even be variable depending on the physicallayer design and the coverage class of the UE. According to certainembodiments, the start criterion of the drx-InactivityTimer could be setto at least a roundtrip time after the uplink transmission but thedetails is left FFS until more details are available from RAN1 on thedownlink NB-PDCCH/PDSCH design. According to certain embodiments,semi-static connected mode DRX parameters for NB-IoT is included as partof RrcConnectionReestablish, RrcConnectionSetup, RrcConnectionResume,i.e. as part of Msg3. According to certain embodiments, the semi-staticconnected mode DRX parameters shall be applied directly when received inthe UE.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of thedisclosure. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic. As used in this document, “each” refers to each member of a setor each member of a subset of a set.

Modifications, additions, or omissions may be made to the methodsdescribed herein without departing from the scope of the disclosure. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. Accordingly, the above descriptionof the embodiments does not constrain this disclosure. Other changes,substitutions, and alterations are possible without departing from thespirit and scope of this disclosure, as defined by the following claims.

Abbreviations used in the preceding description include:

3GPP Third Generation Partnership Project

ACK Acknowledgement

AP Access Point

BS Base Station

BSC Base Station Controller

BTS Base Transceiver Station

CPE Customer Premises Equipment

D2D Device-to-device

DAS Distributed Antenna System

DCI Downlink Control Information

DL Downlink

DRB Data Radio Bearer

DRX Discontinuous Reception

DTX Discontinuous Transmission

eNB evolved Node B

EPDCCH Enhanced Physical Downlink Control Channel

FDD Frequency Division Duplex

HARQ Hybrid Automatic Repeat reQuest

HSPA High Speed Packet Access

IoT Internet-of-Things

LAN Local Area Network

LEE Laptop Embedded Equipment

LME Laptop Mounted Equipment

LTE Long Term Evolution

M2M Machine-to-Machine

MAN Metropolitan Area Network

MCE Multi-cell/multicast Coordination Entity

MCS Modulation level and coding scheme

MIMO Multiple Input Multiple Output

MR Measurement Restriction

MSR Multi-standard Radio

NACK Negative Acknowledgement

NAS Non-Access Stratum

NB Narrowband

NB-IoT Narrowband Internet-of-Things

NB-PDCCH Narrowband Physical Downlink Control Channel

NB-PDSCH Narrowband Physical Downlink Shared Channel

NB-PUSCH Narrowband Physical Uplink Shared Channel

NPDCCH Narrowband Physical Downlink Control Channel

NPDSCH Narrowband Physical Downlink Shared Channel

NPUSCH Narrowband Physical Uplink Shared Channel

OFDM Orthogonal Frequency Division Multiplexing

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PMI Precoded Matrix Indicator

PRB Physical Resource Block

PSTN Public Switched Telephone Network

PHICH Physical Hybrid-ARQ Indicator Channel

PUSCH Physical Uplink Shared Channel

PUCCH Physical Uplink Control Channel

RB Resource Block

RI Rank Indicator

RNC Radio Network Controller

RRC Radio Resource Control

RRH Remote Radio Head

RRU Remote Radio Unit

RTT Round Trip Time

SAW Stop-and-Wait

SRB Signaling Radio Bearer

TDD Time Division Duplex

TFRE Time Frequency Resource Element

UCI Uplink Control Information

UE User Equipment

UL Uplink

WAN Wide Area Network

The invention claimed is:
 1. A method in a user equipment (UE),comprising: monitoring a downlink control channel during a duration ofat least a first timer; receiving, on the monitored downlink controlchannel, an indication of a downlink or uplink transmission for the UE;after receiving the indication of the downlink or uplink transmissionfor the UE, stopping the first timer, wherein after the first timer isstopped the UE does not need to monitor the downlink control channel;performing an uplink transmission associated with the indicated downlinkor uplink transmission for the UE; starting a second timer, afterreceiving the indication of the downlink or uplink transmission for theUE, the duration of the second timer comprising an offset period; whenthe second timer expires, starting a third timer, wherein the UEmonitors the downlink control channel for the duration of the thirdtimer.
 2. The method of claim 1, comprising: entering a discontinuousreception mode when the third timer expires.
 3. The method of claim 1,wherein the first timer is an onDurationTimer of a discontinuousreception cycle.
 4. The method of claim 1, wherein at least one of thefirst timer and the third timer is a drx-InactivityTimer.
 5. The methodof claim 1, wherein at least one of the first timer and the third timercomprises a discontinuous reception retransmission timer.
 6. The methodof claim 1, wherein the second timer is a Hybrid Automatic RepeatreQuest (HARQ)-Round Trip Time (RTT) timer that comprises the offsetperiod.
 7. The method of claim 1, wherein: the indication of thedownlink or uplink transmission for the UE comprises a downlinkscheduling assignment; and the uplink transmission associated with theindicated downlink transmission comprises an acknowledgement message. 8.The method of claim 1, wherein: the indication of the downlink or uplinktransmission for the UE comprises an uplink grant; and the uplinktransmission associated with the indicated uplink transmission comprisesa data transmission in the uplink.
 9. The method of claim 1, wherein theindication of the downlink or uplink transmission for the UE comprisesinformation about a duration of at least one of the second and thirdtimers.
 10. The method of claim 1, comprising receiving a messageincluding information about a duration of at least one of the second andthird timers.
 11. The method of claim 1, wherein the second timer isstarted either: after performing the associated uplink transmission; orat the end of the received indication of the downlink or uplinktransmission for the UE.
 12. A method in a network node, comprising:determining a duration of a first timer and a duration of a secondtimer, the first and second timers for use by a user equipment (UE) tocontrol discontinuous reception operation, wherein the duration of thefirst timer comprises an offset period; and sending, to the UE,information about the duration of the first timer and the duration ofthe second timer; wherein the information about the duration of thefirst timer and the duration of the second timer is included in anindication of a downlink or uplink transmission for the UE.
 13. Themethod of claim 12, comprising: sending, to the UE, an indication of adownlink or uplink transmission for the UE; and receiving, from the UE,an uplink transmission associated with the indicated downlink or uplinktransmission for the UE.
 14. The method of claim 13, wherein theduration of the first timer comprises one of: an amount of time that theUE waits after sending the uplink transmission associated with theindicated downlink or uplink transmission for the UE before the UEstarts the second timer; and an amount of time that the UE waits afterthe end of the indication of the downlink or uplink transmission for theUE before the UE starts the second timer.
 15. A user equipment (UE),comprising: processing circuitry, the processing circuitry configuredto: monitor a downlink control channel during a duration of at least afirst timer; receive, on the monitored downlink control channel, anindication of a downlink or uplink transmission for the UE; afterreceiving the indication of the downlink or uplink transmission for theUE, stop monitoring the first timer, wherein after the first timer isstopped, the UE does not need to monitor the downlink control channel;perform an uplink transmission associated with the indicated downlink oruplink transmission for the UE; start a second timer, after receivingthe indication of the downlink or uplink transmission for the UE, theduration of the second timer comprising an offset period; when thesecond timer expires, start a third timer, wherein the UE monitors thedownlink control channel for the duration of the third timer.
 16. The UEof claim 15, wherein the processing circuitry is configured to: enter adiscontinuous reception mode when the third timer expires.
 17. The UE ofclaim 15, wherein the first timer is an onDurationTimer of adiscontinuous reception cycle.
 18. The UE of claim 15, wherein at leastone of the first timer and the third timer is a drx-InactivityTimer. 19.The UE of claim 15, wherein at least one of the first timer and thethird timer comprises a discontinuous reception retransmission timer.20. The UE of claim 15, wherein the second timer is a Hybrid AutomaticRepeat reQuest (HARQ)-Round Trip Time (RTT) timer that comprises theoffset period.
 21. The UE of claim 15, wherein: the indication of thedownlink or uplink transmission for the UE comprises a downlinkscheduling assignment; and the uplink transmission associated with theindicated downlink transmission comprises an acknowledgement message.22. The UE of claim 15, wherein: the indication of the downlink oruplink transmission for the UE comprises an uplink grant; and the uplinktransmission associated with the indicated uplink transmission comprisesa data transmission in the uplink.
 23. The UE of claim 15, wherein theindication of the downlink or uplink transmission for the UE comprisesinformation about a duration of at least one of the second and thirdtimers.
 24. The UE of claim 15, wherein the processing circuitry isconfigured to receive a message including information about a durationof at least one of the second and third timers.
 25. The UE of claim 15,wherein the processing circuitry is configured to start the second timereither: after performing the associated uplink transmission; or at theend of the received indication of the downlink or uplink transmissionfor the UE.
 26. A network node, comprising: processing circuitry, theprocessing circuitry configured to: determine a duration of a firsttimer and a duration of a second timer, the first and second timers foruse by a user equipment (UE) to control discontinuous receptionoperation, wherein the duration of the first timer comprises an offsetperiod; and send, to the UE, information about the duration of the firsttimer and the duration of the second timer; wherein the informationabout the duration of the first timer and the duration of the secondtimer is included in an indication of a downlink or uplink transmissionfor the UE.
 27. The network node of claim 26, wherein the processingcircuitry is configured to: send, to the UE, an indication of a downlinkor uplink transmission for the UE; and receive, from the UE, an uplinktransmission associated with the indicated downlink or uplinktransmission for the UE.
 28. The network node of claim 27, wherein theduration of the first timer comprises one of: an amount of time that theUE waits after sending the uplink transmission associated with theindicated downlink or uplink transmission for the UE before the UEstarts the second timer; and an amount of time that the UE waits afterthe end of the indication of the downlink or uplink transmission for theUE before the UE starts the second timer.